When we do any matrix operation, Matlab directly shows the result but not the intermediate steps. I need a command or inbuilt matlab function by which I can see all the detail steps of any mathematical calculations like Numerical analysis, Fourier analysis , linear algebra, matrix etc.
You can do this (partially) by hand using the debugging features of Matlab:
http://www.mathworks.it/it/help/matlab/debugging-code.html
Keep in mind that you cannot go through the code of built-in functions (which is proprietary), nor through p-files (which are obfuscated).
Adding to Simone's good answer. You can use F12 to insert breakpoints into your script or you own built function. When you run your script, Matlab will stop at the breakpoints.
Then you can use F10 to debug line by line (Matlab will run your script line by line, and intermediate results will display in workspace).
Or you can use F5 to debug breakpoint by breakpoint (Matlab will run your script until meet next breakpoint, and the current intermediate results shown in workspace)
As suggested above, you can step trough the execution of the code in Matlab (except for the builtin, mex or p-code functions). It can be done like this (from memory, please check proper syntax):
>> dbstop my_function;
>>my_function()
dbstop is used to tell the matlab debugger that you want it to start debugging at some point, in this case at the beginning of my_function. After that, you can use F10 and F9 keys to step through the code. This can be tedious, so if you just want to see which functions where called, there is another option: the matlab code profiler.
>>profile on; my_function(); profile viewer
will start the profiler, monitoring all code execution (a function or whatever you type at the command prompt). "profile viewer" will stop profiling and present a list of all functions that where executed. But this doesn't show you the order in which the functions where called, namely if one function is invoked multiple times.
A more powerful approach is to start profiling with the 'history' turned on, and analyzing the stored profile data. If you need that, I can provide you some example code. Better yet, have a look at this http://undocumentedmatlab.com/blog/undocumented-profiler-options-part-3/ (Matlab should include a link to that blog by default!)
You can observe it by running different segments of your codes at a time and checking output in workspace.
Thanks 2 all for replying but none of the methods are working ....
So I am explaining it once again .... Ex. A = [1 1 0 0]; B = [1; 2; 3; 4]; C = A*B .... Then Matlab gives C=3 as answer....
Now how can I see the intermediate steps ... that's producing the result C=3 .
You cannot see the intermediate steps, matrix multiplication is proprietary code of Mathworks.
@Kuldip,
- If your interest is understanding the mathematics behind it:
Maybe what you are looking for is a CAS (computer algebra system), which works at a symbolic level, as opposed to Matlab which is more oriented to numerical computation. I think Maxima (http://en.wikipedia.org/wiki/Maxima_%28software%29) might be a good option (but note that Matlab also has a symbolic toolbox). But then, for the basic things like how matrix multiplication is performed, you probably need to refer to a text book.
- If what you want is to look at the actual code implementations used in Matlab, you can look at the source code many of the included functions, but some are compiled for speed or for protecting intelectual property. Perhaps you could turn to Octave or Freemat, which are Matlab-compatible open-source projects, meaning that even if some functions are compiled, you could look at the source code to study the underlying algorithms. Or take a look at TAOCP (http://en.wikipedia.org/wiki/TAOCP) by Donald Knuth, or Numerical Recipes or any of the alternatives in http://math.stanford.edu/~lekheng/courses/302/wnnr/nr-alt.html.
@Miguel Thanks , Maxima is a good software ...
Actually I know all the basic things how matrix multiplication is performed , still I want to see it not only for Matrix operations for all other complex mathematical equations, which take long time to solve ..
.
any ways I think now this problem has become a good Research question ....
ha ha haaaa ~
Hello,
In the m-file, write the name of the function. then, right click on the name and select " open ( the name of function)". now you can see the m-file of the function and debug it.
Gyan Chandra Chauthwani
Write the 'syntax' in MatLab command window with some absurd arguments. It will provide you error in some line...
Then click on the particular syntax to see the coding behind the syntax.
For ex: let for 'ode15s'
step-1: write ode15s(1) in command window. (MATLAB will return some error with line numbers.)
step-2: search "Error in ode15s" from the bunch of errors MATLAB returned
step-3: click on "Line number(with underline)" to see the code
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