I am aware that .p files are Matlab protected files. So, I am not trying to access them. However, I was wondering if I could use their output onto the Matlab shell as input to a Matlab program.
What I mean is the following: I have to simulate a dynamic system in Matlab using a controller. Afterwards, I need to assess its performance. This is done by the .p file. Now, the controller behaviour is defined by six distinct variables. I pretty much know their range. So, what I did was create an optimization to find the optimal coefficients. However, when I run the .p file I see that the coefficients I obtained as optimal are in fact not optimal, i.e. my cost function is biased in some way.
So, what I would like to do is to use the output of the .p file (there are always six strings with only two numerical values - so they would be easy to extract if it were a text file) to run a new optimization so that I can understand what I did wrong in my original cost function.
The alternative is finding the parameters starting from my values by trial and error, but considering there are six variables I would prefer a more mathematically pure approach.
Basically, the question is how I can read the output onto the command prompt of a Matlab .p function, and use it as input in a Matlab function.
Thanks for the help!
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I have different matrices to import into a Simulink Matlab function from the workspace. These matrices have all different dimension, which I don´t know at priori.
At the beginning I tried using the block 'constant' putting the data all together in a structure like this:
But then, I cannot pick the right matrix since I don´t know the dimension of each element (and also 'mux' cannot be used to split matrices).
I think I will have the same problem also with the block 'from workspace'.
I was wondering if there is a smart way to import heterogeneous structures like these. I tried also with cell-arrays, but it seems to be not supported by Simulink.
Thanks for any suggestions.
If the data is to be used in a Matlab Function block you could define the workspace matricies as parameters in the model explorer and in the Matlab Function port editor. You then have them accessible inside that function without even needing the "const" blocks or drawing any signals.
Even if your final intent is not to have data into a Matlab Function block those blocks are quite useful for extracting signals from heterogeneous data since you can do some size/type checking in them. Then you can output "simulink friendly" signals for use elsewhere.
Is it possible to see how MATLAB implements some of its commands? For example, the "hess" command on MATLAB reduces a matrix to its upper Hessenberg form. I want to see how it is written in MATLAB because every time I do it by hand, it is not the same as the one MATLAB spits out but according to WolframAlpha, I am doing it correctly.
I have set up a model using SimMechanics. It outputs data at the times where the solver steps to. Is there any possibility to have some kind of dense output such that it is possible to interpolate these data to get the solution at arbitrary points without losing the high order of the integrator?
In Matlab this is easily possible using the function deval after the integration of one of the built-in ODE integrators.
In SimMechanics I can select these integrators, too. Is there some kind of analouge way to deval?
Yes, it's possible, although it's a Simulink functionality, not specific to SimMechanics. In the Configuration Parameters of the model, you can set the model to Produce Specified Output Only (see http://www.mathworks.co.uk/help/simulink/gui/data-import-export-pane.html#bq9_fhw-1), under Data Import/Export. This way, only the outputs you specify will be produced regardless of the time steps taken by the solver.
If I was to create interpolated splines from a large amount of data (about 400 charts, 500,000 values each), how could I then access the coordinates of those splines from another software quickly and efficiently?
Initially I intended to run a regression on the data and use the resulting formula in my delphi program, but that turned out to be a bigger pain than I thought.
I am currently using Matlab but I can use another software if need be.
Edit: It is probably relevant that this data represents the empirical cumulative distribution of some other data (which I already have in a database).
Here is what one of these charts would look like.
The emphasis is on speed of access. I intend to use this data to run simulations on financial data.
MATLAB has a command for converting a spline into a piecewise polynomial. You can then extract the breaks and the coefficients of each piece of polynomial with unmkpp, and evaluate them in another program.
If you are also familiar with C, you could use Matlab coder or something similar to get an intermediate library to connect your Delphi program and MATLAB together. Interfacing Delphi and C code is, albeit a tad tedious, certainly possible (or it was back in the days of Delphi 7). Or you could even write the algorithm in MATLAB, convert the code to C using Matlab coder and from within Delphi call the generated C library.
Perhaps a bit overkill, but you can store your data in a database (e.g. MySQL) from MATLAB and retrieve them from Delphi.
Finally: is Delphi a real constraint? You could also use MATLAB to do the simulations, as you might have the same tools (or even more) available for MATLAB than in Delphi. Afterwards you can just share the results, which I suppose is less speed critical.
My initial guess at doing this efficiently would be to create a memory mapped file in MATLAB using memmapfile, stuff a look-up table with your data into that, then open the memory mapped file in your Delphi code and read the data from that file.
The fastest is most likely a look-up table that you save to disk and that you load and use in your simulation code (although: why not run the simulation in Matlab?)
You can evaluate the spline for a finely-grained list of values of x using FNVAL, and use the closest value of x to look up the cdf.
Is there a way to get the mex file for a built-in MATLAB m- file? If yes, how? If no, does that mean I have to write the C code myself (oh nooo!!!)
The Matlab built-in functions are closed-source. Thus, you won't be able to get the code for them. It is possible to call Matlab functions from C code, though, if that solves your problem.
Depending on the function you want, you can find some of it elsewhere. For example, linear algebra operations are in LAPACK, and you may be able to get something from the source of OCTAVE.