#For loop in matlab code#
It takes a little extra effort the first few hundred times you do it, but after that you stop noticing, and the advantages when you or some other poor soul come to read your code are legion.Increases index by the value step on each iteration, or decreases when the step is negative. tend to advise against them.įor my part I avoid all single-letter variables, despite the obvious advantages for directly implementing mathematical sources. MATLAB doesn't suffer from this and I believe Visual Studio hasn't had a problem for some time, but the C/C++ coding standards like MISRA, etc. Generally, and depending on your IDE, a single-letter variable name can cause havoc with highlighters and search/replace. MATLAB specifically: if you're using coder to generate C++ source from your MATLAB code (don't, it's horrible) then you are explicitly warned not to reuse variables because of potential typing clashes. Of course this is a matter of personal taste as well, but it should not be hard to find indices to use that have a clear meaning without growing too long.Ĭonfusion with the imaginary unit has been well covered here, but there are some other more prosaic reasons why these and other single-letter variable names are sometimes discouraged. Therefore my personal recommendation would be: In case you sometimes work with complex code, always use 1i combined with a different loop variable.Įxamples of single letter indices that for if you don't use many loop variables and letters suffice: t, u, k and pĮxample of longer indices: i_loop, step, walk, and t_now One will not easily be misread for two or three, but two and three resemble each other. Here is an example why (personally) I don't like it: val2 = val + i % 1 However, though these are both fine deviations from i, it is not very nice to use both of these alternatives together.
If you want to use the imaginary number, it can be confused with or overwritten by an index.
For speed and improved robustness, you can replace complex i and j by 1i.Īs described in other answers, the use of i in general code is not recommended for two reasons: However, it is best to avoid using i and j for variable names if you intend to use them in complex arithmetic. Since i is a function, it can be overridden and used as a variable. Here's the extent of MathWorks' actual recommendations, from the current release documentation for i: without saying who's doing that recommending. I see a lot of answers here that say It is not recommended.
#For loop in matlab free#
On the other hand, in my typical work I never deal with complex numbers, and I find my code more readable if I feel free to use i and j as loop indices. If you do a lot of work with complex numbers, you may want to avoid i and j as variables, to avoid any small potential risk of confusion (although you may also/instead want to only use 1i or 1j for even less confusion, and a little better performance). In any recent version, it's really a personal preference whether to use i and j as variable names or not. For a while, MathWorks might even have unofficially advised people to do that themselves (although they always officially advise people to program for elegance/maintainability rather than to whatever the current JIT does, as it's a moving target each version).īut that's rather a long time ago, and nowadays it's a bit of a "zombie" issue that is really much less important than many people still think, but refuses to die. That's why, if you read through much MathWorks code, you'll see ii and jj used fairly widely as loop indices. Your code would therefore get slower just by the very presence of i and j as variables, and would speed up if you changed them to something else. In old versions of MATLAB, there used to be a good reason to avoid the use of i and j as variable names - early versions of the MATLAB JIT were not clever enough to tell whether you were using them as variables or as imaginary units, and would therefore turn off many otherwise possible optimizations.
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