summation

2011 9 28
2 个回答
8 次查看（30 天）

0 个投票

how to implement summation in matlab Is there any function for 2D summation in matlab

请先登录，再回答此问题。

回答（2 个）

TAB
TAB 2011-9-28

1 个投票

A=rand(5);
As=sum(sum(A));

3 个评论
显示 1更早的评论 隐藏 1更早的评论

Jan
Jan 2011-9-28
SUM(SUM(A)) is slower than SUM(A(:) on older Matlab versions (I assume <= 2009a), and on single core machines. On a modern system SUM(SUM(A)) is parallelized and faster in consequence.
Andrei Bobrov
Andrei Bobrov 2011-9-28
Hi Jan!
A= rand(5000);
tic,sum(sum(A));toc
tic,sum(A(:));toc
clear A
Elapsed time is 0.037663 seconds.
Elapsed time is 0.037902 seconds.
MATLAB R2010a, Intel Core2 Duo, 2.13 GHz, 2 GB RAM
TAB
TAB 2011-9-28
On Matlab R2007a , C2D, 4GB RAM
A= rand(5000);
tic,sum(sum(A));toc --> 0.047444 Sec
tic,sum(A(:));toc --> 0.047441 Sec
Yes, Andrei's version is faster. :-)

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Language Fundamentals 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by