Which is faster, a row vector or a column vector? Can anyone answer me please?

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Avan Al-Saffar 2015-5-13

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编辑： Stephen23 2015-5-15

I am trying to do some integration so I am defining the output as a matrix, my question is which definition will give me faster results to define my matrix :

A = zeros(1,n) or A = zeros(n,1)?

Regards

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Stephen23 2015-5-13

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编辑：Stephen23 2015-5-15

在 MATLAB Online 中打开

Perhaps the column, as MATLAB uses column-major memory storage of arrays. But really it is unlikely to make a big difference.

Just try it and use timeit or tic and toc to compare the times.

Another very fast way to define a matrix of zeros is this:

A(n) = 0;

Or if speed really is that critical, you might like to check out some of the submissions on MATLAB File Exchange:

http://www.mathworks.com/matlabcentral/fileexchange/31362-uninit-create-an-uninitialized-variable--like-zeros-but-faster-

My checking shows that if you use 5 for r, and leave s symbolic, then there is a closed-form integral for the expression -- something that could be evaluated once per t rather than having to do the time-consuming numeric integration.

In the case of r held at 5, the integral for turns complex if s becomes larger than about 10.3 or if s is negative (but might become positive again below -10.3).

When you are varying r and s for your 16 runs, what are the values you are testing with?

Avan Al-Saffar 2015-5-15

编辑：Avan Al-Saffar 2015-5-15

r = 1,2.5,5,10

s = 1,3,5,10

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Walter Roberson 2015-5-13

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For any of the arithmetic operations, a row vector is exactly the same speed as a column vector. However, extracting a column vector from a matrix is faster than extracting a row vector. Also, library functions often are defined as returning column vectors and their logic is sometimes marginally faster on column vectors.