For loop and adding elements to an array. How to?

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Solarmew 2015-5-21

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编辑： Stephen23 2015-5-21

I have some function y(x). I would like to generate a list of y values for x between -10^-3 and 10^-3 in 10^-4 intervals and plot y vs x. I'm trying to do something simpler and less messy first for practice:

function test
global x
for n = -5; n < 5; n+1;
    x(end+1)=2*n;
end
end

but this leaves me with x = -10. Why? What am I doing wrong and how could I fix it? Also, is there a way to make an array of x AND their corresponding y values simultaneously and then just plot that one thing? Like list = {{1,1},{2,4},{3,6},{4,8}} and plot this as pairs of coordinates.

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Solarmew 2015-5-21

Yep. Watched a similar example of YouTube. Just realized that the help file I was looking at was for C ... why is there help for C in MatLab? +.+ ... that's the third time already that I try to use some syntax from the help file only to realize that it's not for MatLab ... dafuq ...

Walter Roberson 2015-5-21

Where did you find that help file?

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Answer 1

Stephen23 2015-5-21

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https://ww2.mathworks.cn/matlabcentral/answers/217824-for-loop-and-adding-elements-to-an-array-how-to#answer_179878

编辑：Stephen23 2015-5-21

在 MATLAB Online 中打开

MATLAB is not C or any other low-level programming language that requires loops to solve everything. In MATLAB the standard method is to generate the whole vector at once using the colon operator:

>> x = -10^-3:10^-4:10^-3
x = -0.001 -0.0009 -0.0008 -0.0007 -0.0006 -0.0005 -0.0004 -0.0003 -0.0002 -0.0001 0 0.0001 0.0002 0.0003 0.0004 0.0005 0.0006 0.0007 0.0008 0.0009 0.001

This is faster and neater than using loops: knowing how to write vectorized code makes using MATLAB a lot faster, productive and enjoyable!