There are three reasons I use bsxfun (documentation, blog link) bsxfun is faster than repmat (see below) bsxfun requires less typing Using bsxfun, like using accumarray, makes me feel good about my understanding of MATLAB. bsxfun will replicate the input arrays along their “singleton dimensions”, i.e., the dimensions along which the size of the array … Read more
Can you use R to replace MATLAB? Yes. I used MATLAB for years but switched primarily to R in the last 3 years. At this point, they have much more in common than not. It partially depends on your field and use-case. And as Spencer Graves said previously, it also depends on which “church you … Read more
Apart from timeit which ThiefMaster mentioned, a simple way to do it is just (after importing time): t = time.time() # do stuff elapsed = time.time() – t I have a helper class I like to use: class Timer(object): def __init__(self, name=None): self.name = name def __enter__(self): self.tstart = time.time() def __exit__(self, type, value, traceback): … Read more
Because i and j are both functions denoting the imaginary unit: http://www.mathworks.co.uk/help/matlab/ref/i.html http://www.mathworks.co.uk/help/matlab/ref/j.html So a variable called i or j will override them, potentially silently breaking code that does complex maths. Possible solutions include using ii and jj as loop variables instead, or using 1i whenever i is required to represent the imaginary unit.
I’ve been working with OO MATLAB for a while, and ended up looking at similar performance issues. The short answer is: yes, MATLAB’s OOP is kind of slow. There is substantial method call overhead, higher than mainstream OO languages, and there’s not much you can do about it. Part of the reason may be that … Read more
There are several tools for converting Matlab to Python code. The only one that’s seen recent activity (last commit from June 2018) is Small Matlab to Python compiler (also developed here: SMOP@chiselapp). Other options include: LiberMate: translate from Matlab to Python and SciPy (Requires Python 2, last update 4 years ago). OMPC: Matlab to Python … Read more
MATLAB’s FOR loop is static in nature; you cannot modify the loop variable between iterations, unlike the for(initialization;condition;increment) loop structure in other languages. This means that the following code always prints 1, 2, 3, 4, 5 regardless of the value of B. A = 1:5; for i = A A = B; disp(i); end If … Read more
Use the class function: >> b = 2 b = 2 >> a=”Hi” a = Hi >> class(b) ans = double >> class(a) ans = char
This kind of question is recurring and should be answered more clearly than “MATLAB uses highly optimized libraries” or “MATLAB uses the MKL” for once on Stack Overflow. History: Matrix multiplication (together with Matrix-vector, vector-vector multiplication and many of the matrix decompositions) is (are) the most important problems in linear algebra. Engineers have been solving … Read more
The first function in an m-file (i.e. the main function), is invoked when that m-file is called. It is not required that the main function have the same name as the m-file, but for clarity it should. When the function and file name differ, the file name must be used to call the main function. … Read more