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Re: create variables from struct wihout eval

Steven_Lord — Tue, 21 May 2013 13:39:00 +0000

"Anders " <anders.frisk@afconsult.com> wrote in message
news:knfj5o$nbs$1@newscl01ah.mathworks.com...
> Hi
>
> i'could not find a answer for this on the forum, so please let me know if
> you know a way.
>
> I have a struct TP, it consits of several fields, a different number of
> fields, and of different names depending on inputs. Now I want to create a
> variable for each field, and name the variable the same as the field name.

Why? This is generally considered a Bad Idea; see question 1 in the
Programming section of the newsgroup FAQ for an explanation.

http://matlab.wikia.com/wiki/FAQ

[It used to be question 6 in that section, but ImageAnalyst moved it to
question 1 in that section yesterday.]

> This is done by getfields and by using eval. However, this is done many
> times in my program, and eval is not very efficient, is there anyway to do
> this without utsing eval?
>
> s=fieldnames(TP);
> for j=1:length(s)
> eval([s{j} '(end+1,:)=getfield(TP,s{j})']); end

Not without using SAVE and LOAD and risking "poofing" variables into your
workspace, and that's not going to be any faster than EVAL since it has to
do disk access.

I recommend avoiding doing this with either EVAL or SAVE/LOAD. Just refer to
the fields.

--
Steve Lord
slord@mathworks.com
To contact Technical Support use the Contact Us link on
http://www.mathworks.com

(sensitivity)-TP rate versus (1-Specificity)- FP rate ROC curve

Sadiah — Tue, 21 May 2013 13:28:10 +0000

I want to compare the performance of a segmentation algorithm against ground truth.
The values for both TP rate and FP rate have been determined. How am going to plot the
ROC curve. I tried to plot those values directly in Matlab but the results was not as expected. Are there any other things need to be considered in producing the right ROC curve.

Thanks.

How to create a Human movement model (walking, standing up, sitting down, falling)

Julia — Tue, 21 May 2013 13:19:08 +0000

Hello,

I am the beginner user of MATLAB, I am currently doing my final year project which need to development a software system for elderly assisted living.

It requires me to build human movement model (walking, standing up, sitting down, falling) and get the equations of the model, use Simulink to implement with Tri-axial accelerometers and simulate the sensor data suing those equations. With the signals generated, I can then test the fall detection program.

I have came out with the fall detection algorithm, but it cost me lots of time thinking how to build the human movement model. I'm kind of lost.

If anyone with the experience can guide me in building the model and get the equations. It will help me a lot in the project development!

Thanks and looking forward to the reply!

How to create a Human movement model (walking, standing up, sitting down, falling)

Julia — Tue, 21 May 2013 13:10:09 +0000

Hello,

I am the beginner user of MATLAB and I am currently doing my final year project which need to develop a software system for elderly assisted living.

It require me to build a human movement model (walking, standing up, sitting down, falling), get the equations of the model, use Simulink to implement with Tri-axial accelerometer and simulate the sensor data. With the data, then I can test my fall detection program.

I am able to come out with the fall detection algorithm, but building the human movement model really cost me a lot of time and I am kind of lost.

If anyone with the experience of this part can guide me how to create the model, find the equations, it will help me a lot!

Thanks! Looking forward to the reply!!

Re: how to find the location of maximum in MxN matrix

Alan_Weiss — Tue, 21 May 2013 11:59:57 +0000

On 5/21/2013 7:40 AM, Liaquat Ali wrote:
> Hallo
> Is there any function to find the location of the maximum of the MxN
> matrix ?
> Regards
> Ali
doc max

Alan Weiss
MATLAB mathematical toolbox documentation

Re: Data Conversion

Garba — Tue, 21 May 2013 11:51:09 +0000

TideMan <mulgor@gmail.com> wrote in message <9dbad8fa-0ebf-4846-8bea-3b3ba71eb91a@googlegroups.com>...
> On Tuesday, May 21, 2013 10:08:09 PM UTC+12, Garba wrote:
> > I have a data set, a daily degree data (366 data points) that I want to convert to hourly values (24*366 = 8784 data points). The raw data obtained are averaged hourly values. So I want to reconvert to the hourly values by generating random hourly values that will represent the daily average values. Any hint on a MATLAB script that will do this?
>
> You need to specify both the distribution and the scale parameter.
> e.g., normal distribution with standard deviation of x.
>
> Then you would do this:
> y=ybar*ones(1,24) + x*randn(366,24);
> y=y(:);
> where ybar is a column vector (366 x 1) of daily means.
Thanks very much it works, but when I average the 24 hourly values they dont equal the daily value

Re: speech signal processing

yusra — Tue, 21 May 2013 11:45:13 +0000

"arsalan khan" <ardkhan138@yahoo.com> wrote in message <iursqu$29q$1@newscl01ah.mathworks.com>...
> Hi,
> I want to acquire speech signal of lenght 10 seconds with irregular volume adjustment. Could any one help me in this regard.
>
> Thank you.

hi,
i was looking for speech production through AR model. if u hv found any thing on it please share .. THanks

how to find the location of maximum in MxN matrix

Liaquat Ali — Tue, 21 May 2013 11:40:12 +0000

Hallo

Is there any function to find the location of the maximum of the MxN matrix ?

Regards
Ali

PDF from a Markov Chain

Vevek — Tue, 21 May 2013 11:24:30 +0000

Hi,

I have generated the Markov chain, from the genrated markov chain i need to calculate the probability density function(PDF). How should i do it? Whether i have to use directly the generated Markov chain into any of the pdf function or i have to do any pre-processing of the data before finding the PDF. Need suggestions.

Thanks

Function similar to ISOSURFACE

Gauss Peter — Tue, 21 May 2013 10:50:09 +0000

Hi all,
I need to find a function similar to isosurface, because it give me a lot of problem in an approximation of point cloud 3D, it creates some artifacts on the edge of the figure without a reason. So I need something similar that compute and find the points on the surface but doesnt render it (useless).
Thank you

create variables from struct wihout eval

Anders — Tue, 21 May 2013 10:44:08 +0000

Hi

i'could not find a answer for this on the forum, so please let me know if you know a way.

I have a struct TP, it consits of several fields, a different number of fields, and of different names depending on inputs. Now I want to create a variable for each field, and name the variable the same as the field name. This is done by getfields and by using eval. However, this is done many times in my program, and eval is not very efficient, is there anyway to do this without utsing eval?

                s=fieldnames(TP);
                for j=1:length(s)
                    eval([s{j} '(end+1,:)=getfield(TP,s{j})']);
                end

Re: Data Conversion

TideMan — Tue, 21 May 2013 10:31:16 +0000

On Tuesday, May 21, 2013 10:08:09 PM UTC+12, Garba wrote:
> I have a data set, a daily degree data (366 data points) that I want to convert to hourly values (24*366 = 8784 data points). The raw data obtained are averaged hourly values. So I want to reconvert to the hourly values by generating random hourly values that will represent the daily average values. Any hint on a MATLAB script that will do this?

You need to specify both the distribution and the scale parameter.
e.g., normal distribution with standard deviation of x.

Then you would do this:
y=ybar*ones(1,24) + x*randn(366,24);
y=y(:);
where ybar is a column vector (366 x 1) of daily means.

Data Conversion

Garba — Tue, 21 May 2013 10:08:09 +0000

I have a data set, a daily degree data (366 data points) that I want to convert to hourly values (24*366 = 8784 data points). The raw data obtained are averaged hourly values. So I want to reconvert to the hourly values by generating random hourly values that will represent the daily average values. Any hint on a MATLAB script that will do this?

Re: Error in blas/lapack when linking to external library using mex

Nasser M. Abbasi — Tue, 21 May 2013 08:23:45 +0000

On 5/21/2013 3:12 AM, Vincent wrote:

> Any suggestions on what might cause this error? Does matlab link to a proprietary blas/lapack library?
>

Matlab uses mkl

EDU>> version -lapack

ans =

Intel(R) Math Kernel Library Version 10.3.11 Product Build 20120606 for 32-bit applications
Linear Algebra PACKage Version 3.4.1

see also:

http://en.wikipedia.org/wiki/Math_Kernel_Library

"Intel's Math Kernel Library (MKL) is a library of optimized
math routines for science, engineering, and financial applications.
Core math functions include BLAS, LAPACK, ScaLAPACK, sparse solvers,
fast Fourier transforms, and vector math."

--Nasser

Error in blas/lapack when linking to external library using mex

Vincent — Tue, 21 May 2013 08:12:09 +0000

Hi all,

I'm currently building a connection between an external library package and matlab using mex files. Previously, I assembled the matrices in matlab and subsequently exported/imported them using .mat files. Using a mex file linking to the library, I want to be able to directly call some functions to work on the matrices. The mex file is the working, unchanged C-file plus some changes to exchange inputs and outputs (a routine to transfer sparse matrices).

It compiles fine(both with the -lmwlapack -lmblas or with -llapack -lblas), but when running the mexfile, I get an error stating:
in "(BLAS) invert" at "src/blas/Algebra.cc:268"
Error: invalid argument (argument 4 LAPACK::getrf)

The interesting thing is that it runs just fine in the cpp-file, but it returns this error when running in the matlab environment.

Any suggestions on what might cause this error? Does matlab link to a proprietary blas/lapack library?