Not in school! (maybe...)

LINQ Guidelines

2016-02-23T17:30:00.000+08:00

1. As the name suggests, LINQ is a query, it is preferred not to have side effects.
2. Use Any() instead of Count() > 0 when you need to find out if a list is not empty.

[WPF] Scroll on new item for ItemsControl, ListView, DataGrid, etc.

2015-12-26T00:45:00.000+08:00

Can be achieved using behaviors.

[WPF] Binding a Storyboard property relative to the target of the storyboard

2015-12-25T14:19:00.002+08:00

In my search to achieve making application level storyboards with some changeable properties:

http://stackoverflow.com/questions/4472546/binding-a-storyboard-property-relative-to-the-target-of-the-storyboard

Binding a Storyboard property relative to the target of the storyboard

up vote 8 down vote favorite

I have a storyboard which targets an element, and binds one of its own properties to a property on another element:


   
            Storyboard.TargetProperty="RenderTransform.X" 
            From="{Binding RelativeSource={RelativeSource AncestorType={x:Type Window}}, Path=ActualWidth}" 
            To="0" 
            Duration="0:0:5"/>

This storyboard works when the storyboard is stored in the resources of the window which holds the storyboard target. The 'From' value is correctly bound to the ActualWidth of the host Window instance.

However, I need to store the storyboard in my application level resources. From here, the storyboard does not seem to be able to target the window to determine the 'From' property. This is understandable as from inside , the binding won't be able to find an 'ancestor' of type Window.

I guess I need to be able to bind the 'From' value, relative to the target of the animation, rather than relative to the storyboard's DoubleAnimation.

Is this possible, and if so, how?

Here is the sample MainWindow.xaml:


    
     x:Key="localStoryBoard">
         
            Storyboard.TargetProperty="RenderTransform.X" 
            From="{Binding RelativeSource={RelativeSource AncestorType={x:Type Window}}, Path=ActualWidth}" 
            To="0" 
            Duration="0:0:5"/>

RoutedEvent="Button.Click"> Storyboard="{StaticResource centralStoryBoard}"/>
And here is an example app.xaml:

 x:Class="WpfApplication3.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             StartupUri="MainWindow.xaml">
    
        
         x:Key="centralStoryBoard">
             
                Storyboard.TargetProperty="RenderTransform.X" 
                From="{Binding RelativeSource={RelativeSource AncestorType={x:Type Window}}, Path=ActualWidth}" 
                To="0" 
                Duration="0:0:5"/>

This won't work, as the eventtrigger refers to the app.xaml version. If you change it to the local resource version, you can see it works.

[WPF] Binding to attached property

2015-12-25T14:17:00.003+08:00

I'm trying to make a storyboard as an application resource where I can set a variable objects such as TO and FROM color transitions, the length of time between transitions, this seems like a good candidate:

http://stackoverflow.com/questions/19769263/binding-to-attached-property

2 down vote favorite

I'm trying to bind from Button's ContentTemplate to attached property. I read all the answers for question similar to "binding to attached property" but I had no luck resolving the problem.
Please note that example presented here is a dumbed down version of my problem to avoid cluttering the problem with business code.
So, I do have static class with attached property:

using System.Windows;

namespace AttachedPropertyTest
{
  public static class Extender
  {
    public static readonly DependencyProperty AttachedTextProperty = 
      DependencyProperty.RegisterAttached(
        "AttachedText",
        typeof(string),
        typeof(DependencyObject),
        new PropertyMetadata(string.Empty));

    public static void SetAttachedText(DependencyObject obj, string value)
    {
      obj.SetValue(AttachedTextProperty, value);
    }

    public static string GetAttachedText(DependencyObject obj)
    {
      return (string)obj.GetValue(AttachedTextProperty);
    }

  }
}

and a window:

<Window x:Class="AttachedPropertyTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:AttachedPropertyTest"
        Title="MainWindow" Height="350" Width="525">
  <Grid>
    <Button local:Extender.AttachedText="Attached">
      <TextBlock 
        Text="{Binding 
          RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Button},
          Path=(local:Extender.AttachedText)}"/>
    </Button>
  </Grid>
</Window>

That's pretty much it. I would expect t see "Attached" in the middle of the button. Instead it crashes with: Property path is not valid. 'Extender' does not have a public property named 'AttachedText'.
I've set breakpoints on SetAttachedText and GetAttachedText, and SetAttachedText is executed, so attaching it to button works. GetAttachedText is never executed though, so it does not find property when resolving.
My problem is actually more complicated (I'm trying to do binding from inside of Style in App.xaml) but let's start with the simple one.
Did I miss something? Thanks,

3 down vote accepted

Your attached property registration is wrong. The ownerType is Extender, not DependencyObject.

public static readonly DependencyProperty AttachedTextProperty = 
    DependencyProperty.RegisterAttached(
        "AttachedText",
        typeof(string),
        typeof(Extender), // here
        new PropertyMetadata(string.Empty));

See the MSDN documentation for RegisterAttached:

ownerType - The owner type that is registering the dependency property

[WPF] SharedSizeGroup IsSharedSizeScope Grid inside UserControl

2015-12-25T00:05:00.001+08:00

While I can't confirm for sure that your requirement will work, I can confirm that as long as you set the Grid.IsSharedSizeScope Attached Property to True on a parent container control of both of the Grids that you have set up SharedSizeGroups for, then it should work. To find out for sure, just try it out... you could have probably tested it yourself quicker than the time it took you to write this question.

If there is no parent container control at the moment, just add one.... (put everything into it). The important thing to note here is that you're only supposed to set Grid.IsSharedSizeScope to True on the one single parent container control and not on every Grid.

SET Grid.IsSharedSizeScope in the PARENT control! NOT ON THE GRID ITSELF!

http://stackoverflow.com/a/26282796/2547795

[WPF] ListView Item spacing

2015-12-25T00:01:00.002+08:00

Hopefully this will save someone else time. I found there are multiple 
properties that have to be set to 0 in order to completely remove the 
spacing between ListViewItems in a ListView control. In addition to 
Margin and Padding I had to set the BorderThickness to 0.

http://stackoverflow.com/a/11423018/2547795

C# .net Convert bool to int

2013-01-09T19:24:00.001+08:00

bool theBool = true;
int boolToInt = theBool ? 1 : 0; //1 if theBool is true and 0 if theBool is false

that's it.

Failed to complete operation Visual Studio 2008 2010

2012-09-25T20:47:00.000+08:00

Sometimes, when compiling and running a source code in Visual Studio, you get the error "Failed to complete operation" and the project will not run although you have build successfully. You'll know that the build is successful if you try to run the application by going to the BIN folder and running the compiled binary manually. I've been trying to find answers to this error but I've not bumped into a solution until now. Before I tell you the solution I've found, let me tell you how I usually fix it. To make the application run again, I try to do several things after and before I open Visual Studio.

1. If Visual Studio is already open and I'm feeling lazy, I try to do a Build > Clean Solution , then a Build > Rebuild All. This will usually not work. I follow this up by going to the bin folder and deleting the remaining files in the Bin folder. This will leave 1 file which is vshost.exe. If it still does not work, I run the vshost.exe manually.

2. If the above doesn't work (which usually doesn't). I have to close Visual Studio and delete the BIN and OBJ folders manually. This method worked 100% of the time.

This just sucks. There's also no log file that tells you what's wrong as far as I know.

AND NOW... let me tell you how to fix this permanently.

I was using a c# WPF for .net 4.0 project for this and I don't know if this is the same with other projects. I haven't had the need to investigate yet. Please comment if it works on other types of projects. Here are the Steps:

1. Go to the Property Pages of the project your working on. This can be done by selecting the project in the Project Explorer then going to View > Property pages or via the keyboard shortcut SHIFT+F4.

2. In the property pages, go to the Debug page and under Enable Debuggers, [UNCHECK] Enable the Visual Studio hosting process. Note: You'll have to do this for the target configuration (e.g. Release, Debug) or you can just select under the Configuration: pull down menu "All Configurations" to apply it across all future builds.

That's it. Please Comment if this worked for you.

Tags:
Program not running after Run or Compile F5
Failed to complete operation

Errors encountered on Rx (Reactive Extensions) HOL (Hands on Lab)

2012-08-02T05:44:00.003+08:00

Problems doing HOL
Error doing HOL
Hands on labs errors

Reactive extensions (Rx) in .Net intends to solve the nightmares of asynchronous programming. The concept is really new to me and I tried doing the Rx Team's HOL (Hands on Lab) for Rx in C#. Since the HOL was last updated a number of changes have been made. These are the troubles I encountered while doing the Rx HOL.

1.

source.Run( x => Console.WriteLine("OnNext: {0}", x), ex => Console.WriteLine("OnError: {0}", ex.Message), () => Console.WriteLine("OnCompleted") );

Solution: Use ForEach or Do.
See: http://social.msdn.microsoft.com/Forums/en-US/rx/thread/398452c2-c97d-4d96-b784-2a2e8a026d12

2. Cannot create a breakpoint inside lambda expression, lambda statement:

Solution: The answer is actually on the HOL pdf. But if you are stupid like me and thought you could set a breakpoint the usual way then how wrong you are. It took me a few minutes to find out that a breakpoint cannot be set inside a lambda expression by clicking on the grey bar or by Pressing F9. The way to do it is to click inside a statement then press F9.

e.g. Click on the OnNext word inside WriteLine() then press F9.

3.

var moves = Observable.FromEvent(frm, "MouseMove");

Solution: Use FromEventPattern instead.

var moves = Observable.FromEventPattern(frm, "MouseMove");

using (new CompositeDisposable(movesSubscription, inputSubscription))

Solution: Fully qualify it.

using (new System.Reactive.Disposables.CompositeDisposable(movesSubscription, inputSubscription))

var moves = Observable.FromEvent(frm, "MouseMove");
var input = Observable.FromEvent(txt, "TextChanged");

Solution: Same as 3. Use FromEventPattern

var moves = Observable.FromEventPattern(frm, "MouseMove");
var input = Observable.FromEventPattern(txt, "TextChanged");

6. ObserveOn(lbl) error HOL.

using (input.ObserveOn(lbl).Subscribe(inp => lbl.Text = inp))

Solution: Make sure you add System.Reactive.Windows.Forms as a reference

7. DictServiceSoapClient not found

var svc = new DictServiceSoapClient("DictServiceSoap");

Solution: Add a add a "using" to the header with the namespace of the service reference you created.
e.g. using RxLab.DictionarySuggestService;

Tags: C# RX, c# reactive extensions

Error: The version of the .NET Framework launch condition '.NET Framework 4' does not match the selected .NET Framework bootstrapper package

2012-07-13T02:42:00.001+08:00

After trying out the solutions suggested on THIS PAGE and still didn't get the issue resolved, I found the solution, the fix, the answer!

The primary fix suggested by the people there is:

1. Main Project Properties - Compile Tab - Advanced Compile Options - Target Framework
Pics for step 1:

2. Deployment Project Properties - Prerequisites - Correct Framework checked.
Pics for step 2:

3. Right-click on Deployment project - View - Launch Conditions. In the Launch Condition tab, right-click the .Net Framework Launch condition, then show Properties Window. In the Properties Window, make sure that the Version property is the correct Framework.
Pics for Step 3:

How I SOLVED it:

If after doing the above steps you still have the error try this:
1. Right Click the Installer Project, on View > Launch Conditions.
2. Click on .Net Framework
3. On the Properties page, Change the Version to Any.

4. Rebuild the solution.
5. Change the Version back to your target framework. In my case it's .NET Framework 4.

That's it. The warning message disappeared after I did this. I don't know why it happens but I fixed it this way.

C#, Visual Studio 2010,

IB API, reqMktDataEx : error code 200 no security definition has been found for the request

2012-07-11T06:03:00.001+08:00

Have you ever encountered this error? I can't figure out for the life of me what is wrong with my IContract. I've made it exactly as it is on the VB.NET sample they included but I'm still getting "error code 200".

I tried using reqMktData() and thankfully it worked! But I am not satisfied. I want to find out what's wrong with my IContract. Here's the inspection before the parameters are passed to reqMktDataEx()

If you've encountered the same error, please share on how you solved it.

EDIT 5 minutes later:

I solved it damn it.

After calling Tws.CreateContract(), do not change IContract.conId ..

why do I need hours to solve such problems... these guys need to work on their documentation.

=======================
oTws.reqMktDataEx(quote.TickerId, quote.contractInfo, quote.GenericTicks, (int)quote.Snapshot);



+	quote
	quote.GenericTicks		string
	quote.Snapshot	0	int?
	quote.TickerId	1	int
-	quote.contractInfo	{System.__ComObject}	TWSLib.IContract {System.__ComObject}
+	[System.__ComObject]	{System.__ComObject}	System.__ComObject
	comboLegs	null	dynamic
	conId	1	int
	currency	USD	string
	exchange	SMART	string
	expiry		string
	includeExpired	0	int
	localSymbol		string
	multiplier		string
	primaryExchange	NASDAQ	string
	right		string
	secId		string
	secIdType		string
	secType	STK	string
	strike	0	double
	symbol	AAPL	string
	underComp	null	dynamic
-	Dynamic View	Expanding the Dynamic View will get the dynamic members for the object
	comboLegs	null
	comboLegsDescrip		System.String
	conId	1	System.Int32
	currency	USD	System.String
	exchange	SMART	System.String
	expiry		System.String
	includeExpired	0	System.Int32
	localSymbol		System.String
	multiplier		System.String
	primaryExchange	NASDAQ	System.String
	right		System.String
	secId		System.String
	secIdType		System.String
	secType	STK	System.String
	strike	0	System.Double
	symbol	AAPL	System.String
	underComp	null

=======================

IBAPI, TWS API, TWSAPI,

Is Lazada Philippines a scam?

2012-06-28T19:11:00.000+08:00

MY experience purchasing at www.lazada.com.ph . A scam or not?

Update Jul 13:

So in the end, I decided to refund my order since more than a month passed since I paid for the item. It seems like they don't track how my orders have been placed on a particular item so what they have in inventory will not match what is displayed on the website. A TYPICAL CASE OF OVERBOOKING -- similar to what budget airlines do. This is the primary reason why potential lazada.com.ph SHOULD AVOID PURCHASING. Imagine how much hassle it would cost you if you paid for an item but you are kept in the dark whether it will arrive or not -- for more than a month. A call from them would have mitigated my frustration BUT THERE WAS NO CALL NOTIFYING ME THAT I WON'T BE RECEIVING MY ITEM. At first, I had to contact them by email which took 5 days to more than a week before I got a response and some were ignored. I tried their hotline which usually made me wait for 5-10minutes and give a different response every time and different from their online support. Imagine doing this for a month. They promise to call you once they get an update but they never do unless you call them a third time within a day. Holy crap impossible. Online merchants from sulit and tpc do way better than these guys.

When I finally decided to refund the item, they said that it would take 1-3 business days. But really, I had to follow up 3 times and took 5 days for it to be refunded. Add the 3day check clearing time to that and it took a grand total of 8 days. They said that they'll email me a scan of the deposit slip but all that I got is a text email 2 days after the check was deposited in my account.

In the end, I finally bought the item from a merchant in tpc. I had to spend 180p for the shipping and it cost 500p more in total. They have a promo that gives 300 pesos discounts on orders 1200p up. The item I was ordering costs approx 1100k+, so I decided to order another item that costs 350+ so that I can avail of the promo. The thing is that the 300p discount will be divided on the items. The 1100+ item got the 250+ discount and the 350+ item got about 50p discount. I received the 350+ item a week after I paid for the item which is the item I did not really need. And the 1100+ peso item that I really intended to buy did not arrive. I only got the item I did not intend to buy which I paid 300 pesos for. I RECEIVED THE ITEM I DID NOT REALLY WANT, AND PAID FOR IT WHICH WOULD HAVE BEEN ALMOST FREE IF I RECEIVED THE INTENDED ITEM. YES, THAT'S RIGHT. I FEEL LIKE I WAS SCAMMED into buying an item that was supposed to be free.

So, this transaction cost me:

About an hour to pay for the items
Over a month of waiting
Hours emailing support
Hours waiting on their hotline
Mental torture because of missed promises
40% more cash spent on the actual item

Final Verdict on lazada.com.ph:

DEFINITELY AVOID AT ALL COSTS.
*Unless you live in metro manila and you can avail of Cash on Delivery (COD) then you'll have more peace of mind since you won't be charged unless the items arrive. The only case I'll warn you is if they ship the items individually, and the cheaper items arrive first, then you are probably in trouble.

------------------------------

It might be a legit business but god damn are they disorganized. one of the items i ordered didn't arrive because they said that it's out of stock. THEY hAD THE FRIGGIN ITEM LISTED ON THEIR WEBSITE FOR 7 DAYS AFTER I RECEIVED THE FIRST ITEM SO WHY ARE THEY TELLING ME THAT IT'S OUT OF STOCK. WHY DID THEY HAVE IT LISTED FOR 7 DAYS IF THEY HAVE NO STOCK.

If I were you, look somewhere else. god damn.

FREE Courses from Stanford and other famous universities

2012-04-27T19:13:00.001+08:00

More free classes are available from Standford and other famous universities. How I wish these were available during my time at college. They would have been a great supplement to my professors. Maybe you might be wondering why there are still universities while you can attend online. It's not really the lectures, it's the environment in a university that drives people to do go there. Having a place to study and find people to talk to is the best environment for innovation as opposed to being cooped up in a room. It may work for some people but for most it isn't really inefficient. Just imagine the difference between asking an expert and looking through a book for an answer.

Anyway, you can find these free courses on www.udacity.com and coursera.org

Some of the courses available are:

@Udacity.com
cs101: Building a Search Engine
cs212: Design of Computer Programs
cs253: Web Application Engineering
cs262: Programming Languages
cs373: Programming A Robotic Car
cs387: Applied Cryptography

@coursera.org
Coursera offers a wider variety of courses, not just computer science. You can see the full list on https://www.coursera.org/courses

Globe Tattoo Broadband Bandwidth Download Cap Limit : What is your real speed?

2012-03-06T05:55:00.002+08:00

ERRATA: may dagdag palang 699 ang PLDT DSL 1.5mpbs 999 dahil hindi pala ito puwedeng kunin na walang landline. But now, PLDT DSL has a similar offer 1299 1mpbs+landline.

Yes.. May limit, may cap, ang downloads.. according sa TPC thread:

http://www.tipidpc.com/viewtopic.php?tid=255402&page=7

ay meron. confirmed.

2mbps + Landline = 1299
Bandwidth cap: 150GB/month WITHOUT Speedboost
3GB/day WITH Speedboost

Pag na reach mo na ang CAP, 30% na lang ng speed mo so 600kbps. Pero yung iba sabi 300kbps lang daw kahit 2mbps. baka typo lng naman..

2mbps ang globe tapos may landline pa! 1299 lang! ang mura di ba?? mura nga ba?? KASO MAY LIMIT!
1.5mbps PLDT DSL internet lang 999! parang mahal!
anu ba talaga??? mas sulit nga ba ang globe kahit may LIMIT?? o ang PLDT na 1.5mbps pero walang limit???

MONTHLY REAL SPEED COMPUTATION 12hours/day FULL USE.

Hmmn... Kung adik ako...

Assume natin wasak lagi 2mbps dahil may 3 nagamit ng net sa bahay.. 12 hours nag iinternet... everyday..

2mbit / s * 12 hours/day * 60minutes/hour * 60 seconds/minute * 1byte/8bits = 10,800 mbyte/day

Kung 150 gig ang limit... it will take only __ days para maubos.

150,000mbytes / 10800mbyte/day = 13.89 days.

13.89 days lang ubos na ang cap.

so the remaining 16.11 days ay 30% ng 2mbps = 600kbps lang ang speed mo....

so ang totoong speed mo within 30 days ay.....

(16.11 days * 2mpbs * 30% + 13.89 days*2mpbs ) / 30days = 1.2482 mbps

tama ba computation ko??? lewlz... this is an approximation na 12hours lang online.. pano pa kung 24hours bukas pc?? whew. pldt n lng cguro 999 1.5mbps.

24 HOUR/day ONLINE REAL SPEED.

2mbit / s * 24 hours/day * 60minutes/hour * 60 seconds/minute * 1byte/8bits = 21,600 mbytes/day

Cap 150 GB will be expended in ___ days:

150,000mbytes / 21600mbyte/day = 6.94 days.

so the remaining 23.06 days ay 30% ng 2mbps = 600kbps lang ang speed mo....

so ang totoong speed mo within 30 days ay.....

(23.06days * 2mpbs * 30% + 6.94 days*2mpbs ) / 30days = 0.923867 mbps

Ay susmaryosep...... so Kung 24 hours ka online panalo ka pa rin sa PLDT na 1.5mbps.. sheeesh. well sino nga naman ba ang mag aabala magonline 24hours. nangyayari lang to kung tatlo kayo sa bahay tapos relyebo kayo dahil sa trabaho.. sa mga dadownload dyan 10 - 24hours at di naman kailangan ng landline palagay ko mas maigi PLDT DSL 999 1.5mbps all else equal.

Kung ayaw mo macap, dapat ang average hours lang ng download mo per day ay:

5000mbytes / 2megabits/s *8bits/byte* 1minute/60seconds * 1hour/60minutes = 5.55 hours of full downloads.

Conclusion KO:

GLOBE 1299 2mbps DSL + Landline:
1. Kung di naman kayo paladownload at tamang FB youtube lang less than 6hours/day... ok sya siguro dahil di nyo mauubos yung 150GB a month.
2. Kung kailangan ng landline sulit. NOTE: di ko alam landline quality ng globe.
3. Sa mga Gamer.. Mataas ping nya sa ibang lugar. lalo na wimax.
4. In General: Kung di ka naman paladownload ng malalaking files pero pag kailangan mo ng extra speed pag nag online ka at kailangan mo ng landline ay puwede ang GLOBE DSL sayo..

PLDT 999 1.5mbps DSL:
1. Kung pala download ka at 10-24hours/day ka nagdadownload
2. Sa experience ko stable ang ping ng PLDT DSL kaya ok sya sa gaming.
3. Sa streaming, kung di naman HD yan.. palagay ko naman walang epek yung diprensya nilang 500kbps. At dahil WALANG CAP ang PLDT, umasa kang di babagal yang youtube streaming anyday.
4. In General: Kung araw araw ka nagdadownload at youtube at gaming tapos di mo maafford na bumagal ang speed mo ng 600 kbps ~~at di mo kailangan ng landline ay PLDT DSL~~ ang malamang na mas kailangan mo.

Kung kelan nyo tulong sa computation with your needs I'll try to help. Wala ako masasabi sa line quality marami nyan info sa net. pero yung computation ng actual needs nyo I can help. kung may mali ako sa computation pakicomment!

TAGS:

GLOBE DSL MAS SULIT sa PLDT DSL? ang katotohan
GLBOE DSL 1299
GLOBE DSL 1299
2mbps + landline
PLDT DSL 999
1.5 mbps
THE TRUTH ABOUT GLOBE'S SPEEDS.
GLOBE OR PLDT DSL?
WHICH IS FASTER GLOBE DSL OR PLDT DSL?

WinToFlash Missing or Corrupt: hal.dll bootsect.dos

2011-10-01T22:55:00.000+08:00

I/O Error accessing boot sector file multi(0)disk(0)partition(1)\bootsect.dos
"Windows could not start because the following file is missing or corrupt: \system32\hal.dll"

Are you having a missing hal.dll error after installing xp from a USB flash drive made by WinToFlash??? The solutions I found didn't work or were too complicated. If you get the error below, all you need to do is boot from the same USB flash drive again. When the splash screen appears, just select the option below the DEBUG option (DEBUG is the third option, so select the fourth). No need to edit the boot.ini for now, you could do it later when you can use windows already.

NOTE: If the fourth option doesn't work, try the other options BUT remember their partition number. The partition number is the number enclosed by parenthesis after the word partition in the option label.

NEXT STEP: editing boot.ini

How to edit the Boot.ini file in Windows XP

Machine Learning Posted Lectures as of Sep 28W11

2011-09-28T22:57:00.000+08:00

Do you want a preview of what you'll learn when you take Stanford's FREE Machine Learning Class? Here are the posted lectures as of Sep 28, Wednesday, 2011. The class officially starts on Oct 10M11 but they have decided to have a few lectures posted in advance.

Machine Learning Preview:

I. INTRODUCTION

Welcome
What is Machine Learning?
Supervised Learning
Unsupervised Learning

II. LINEAR REGRESSION WITH ONE VARIABLE

Model Representation
Cost Function
Cost Function - Intuition I
Cost Function - Intuition II
Gradient Descent
Gradient Descent Intuition
Gradient Descent For Linear Regression
What's Next

III. LINEAR ALGEBRA REVIEW (OPTIONAL)

Matrices and Vectors
Addition and Scalar Multiplication
Matrix Vector Multiplication
Matrix Matrix Multiplication
Matrix Multiplication Properties
Inverse and Transpose

Intro to Databases Posted Lectures as of Sep 28W11

2011-09-28T22:33:00.001+08:00

Do you want a preview of what you'll learn when you take Stanford's FREE Introduction to Databases class? Here are the posted lectures as of Sep 28, Wednesday, 2011. The class officially starts on Oct 10M11 but they have decided to have a few lectures and assignments posted in advanced.

Database Class Preview:

INTRODUCTION

Introduction to the course (14 min)

RELATIONAL DATABASES

The relational model (9 min)
Querying relational databases (6 min)

XML DATA

Well-formed XML (13 min)
DTDs, IDs & IDREFs (18 min)
XML Schema (13 min)

RELATIONAL ALGEBRA
Prerequisite: Relational Databases

Select, project, join (18 min)
Set operators, renaming, notation (20 min)

SQL
Prerequisite: Relational Databases; Recommended: Relational Algebra

Introduction to SQL (5 min)
Basic SELECT statement (10 min)
Table variables and set operators (11 min)
Subqueries in WHERE clause (20 min)
Subqueries in FROM and SELECT (8 min)
Aggregation (25 min)
NULL values (6 min)
Data modification statements (15 min)

FREE Machine Learning Class by Stanford now up! Enroll before start on Oct 10!

2011-09-28T17:53:00.000+08:00

The Machine Learning class offered FREE by Stanford University is now OPEN. The class officially starts on October 10 but some video lectures and assignments are up. Enroll now before the class officially starts!

Enroll now at:

http://www.ml-class.org/

FREE "Intro to DataBases" class by Stanford now running! Enroll before Official start Oct 10

2011-09-28T17:49:00.002+08:00

The Introduction to Databases class offered FREE by Stanford University is now OPEN. The class officially starts on October 10 but some video lectures and assignments are up. Enroll now before the class officially starts!

Enroll now at:

http://www.db-class.org/

Intuition for the Dot Product and the Cross Product

2011-09-14T22:13:00.000+08:00

Often, we know how to solve things by formulas and we accept whatever was given to us. One thing we are forgetting is that these formulas actually mean something. The video below is a great example how to break in to learners that mathematical abstractions are more than just patterns..

Dot product intution:

One of the main point is how the dot product measures how much two vectors go in the same direction. Sal did just dot.

Cross product intuition

The second topic of this video is how the cross product measures how much two vectors are perpendicular to each other. He also explained how the length of the cross product equals the area of the parallelogram the two vectors create.

One thing Sal could have added to this video is why we get negative values. Well, he might have had left that undiscussed for the viewer to think about.

Full video:

Cross and Dot Product intution

Easier Subtraction: Do all your borrowings first!

2011-09-13T23:42:00.001+08:00

Are you having difficulties performing subtraction? Maybe you're just having trouble with the constant switching between borrowing and actually subtracting as thought traditionally in school. Why have they never taught us to do all the borrowing first so that all the actual subtraction is done in one fell swoop? In this video at KhanAcademy.org, Sal teaches a different approach and much more intuitive method to subtraction.

Full video:

Subtraction: Do all your borrowings first!

Lattice Multiplication: Easier multiplication fr: KhanAcademy.org

2011-09-12T23:35:00.000+08:00

Lattice multiplication is a very neat way of multiplying non-single digit quantities. It eliminates the need of switching to and from multiplication and addition. In Lattice multiplication, all multiplication is done before the addition is done. The process is fairly simple:

1. Create a matrix with the number of columns equal to the number of digits of the first number and the number of rows equal to the number of digits of the second number. In the example above, there first and second number both have 2 digits, hence the 2 x 2 matrix.

2. Draw a diagonal in each cell starting from the upper right corner down to the lower left corner.

3. Each row correspond to a digit of the second number and Each column correspond to a digit of the first number. To get the value of each cell, simply multiply the corresponding column value times the column value then the first digit of the product is put on the upper left triangle while the second digit of the product is put on the lower right triangle. We are ensured that there are only 2 digits for any product since the only possible value for each column and each row only ranges from 0 to 9. This means that the maximum result of any product is 9 times 9 or 89. In cases that the product of the cell is only one digit, the product is put on the lower right triangle and zero is put on the upper left triangle. For example, Column 1, row 1 correspond to the digits 2 times 4 and the product is 8. 8 is put on the lower right triangle and zero is put on the upper right triangle.

4. The addition is done. Each diagonal represent a digit in the result. the lower right diagonal is the ones place, the diagonal just above the lower right corner represents the tens place, the diagonal just below the upper left corner represents the hundreds place, and the upper left corner represents the thousands place. To get the result, add the digits in the diagonal and carry over the first digit of the product to the next diagonal.
In the example, there is only one element in the diagonal so we know that the value in the ones place is 6. The digits in the tens diagonal are 8, 5, and 6 which have a sum of 19 that makes the value of the tens place as 9 and 1 is carried over to the hundreds diagonal. The hundreds diagonal have the digits 2, 8, 1, and the carried over 1 from the tens place resulting a sum of 12, this makes the value of hundreds to be 2 and 1 is carried over to the thousands place. The thousands place only have 0 and 1 carried over from the hundreds place which makes the value of the thousands place to be 1. This makes the product of 27 and 48 to be 1296.

Full video:
Lattice Multiplication at KhanAcademy.org

An explanation of why it works:
Why Lattice multiplication works

AI Class Pre Requisites Videos up!

2011-09-10T23:01:00.001+08:00

AI Class has posted the recommended prerequisites videos from KhanAcademy that will help you polish up your math needed for the AI Class. Go check it out in the Other Resources link after you log-in on the my profile page. At the time of this posting, these are the topics posted:

Probability Prerequisites

Basic Probability
Probability (Part 6) [Conditional Probability]
Probability (Part 7) [Bayes' Rule]
Probability (Part 8) [More Bayes' Rule]
Introduction to Random Variables
Probability Density Functions
Expected Value: E(X)

Linear Algebra Prerequisites

Introduction to Matrices
Matrix Multiplication (Part 1)
Matrix Multiplication (Part 2)
Inverse Matrix (Part 1)
Inverting Matrices (Part 2)
Inverting Matrices (Part 3)
Matrices to Solve a System of Equations
Singular Matrices
Introduction to Vectors
Vector Dot Product and Vector Length
Defining the Angle Between Vectors
Cross Product Introduction
Matrix Vector Products
Linear Transformations as Matrix Vector Products
Linear Transformation Examples: Scaling and Reflections
Linear Transformation Examples: Rotations in R2
Introduction to Projections
Exploring the Solution Set of Ax = b
Transpose of a Matrix
3x3 Determinant
Introduction to Eigenvalues and Eigenvectors

Sulit Hi 5!

2011-09-02T23:03:00.001+08:00

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SF Clan Management Tool Version 1.2.1

2010-08-24T03:06:00.000+08:00

WARNING: MAKE SURE YOU DOWNLOAD ONLY FROM THIS WEBSITE. THIS PROGRAM IS GUARANTEED KEYLOG FREE. I WILL NOT BE HELD RESPONSIBLE FOR THE USER'S NEGLIGENCE OF USING SOFTWARE FROM THIRD-PARTY SOURCES.

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