在Matlab中有效访问矩阵中的元素

Question

I have an mxn matrix of integers and where n is a fairly big number m and n ~1000. I want to iterate through all of these and perform a some operations, like accessing a particular cell and assigning a value of a particular cells.

However, at least in my implementation, this is rather inefficient as I have two for loops with Matrix(a,b) = Matrix(a,b+1) or something along these lines. Is there any other way to do this seeing as my current implementation takes a long time to traverse through about 100,000 cells and perform some operations.

Thank you

Answer 1

In matlab, it's almost always possible to avoid loops. If you want to do Matrix(a,b)=Matrix(a,b+1) , you should just do Matrix2=Matrix(:,2:end);

If you are more precise about what you do inside the loop, I can help you more.

Answer 2

Matlab uses column major ordering of matrixes in memory (unlike C). Are you sure you are iterating the indexes in the correct order? If not, try switching them and see if performance improves..

Answer 3

如果您无法摆脱for循环，则一种可能是用C重写昂贵的操作并按此处所述创建MEX文件。