Skipping calculations using if

Question

Tom 2013-12-3

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/108445-skipping-calculations-using-if

编辑： Matt J 2013-12-3

Hello,

I have the following code:

for j = 1:(length(acalc)-1)
    for ii = (j+1):length(acalc)
    dotp(count2,:) = dot(acalc(j,:),acalc(ii,:));
    magp(count2,:) = mag(j)*mag(ii);
    count2 = count2 + 1;  
    end
end

Which works fine if length(acalc) > 1. However when length(acalc) = 1 (as it sometimes is), an error is returned presumably because of the failure in accessing acalc(ii,:) = acalc(j+1,:) = acalc(2,:)

Could someone help me resolve this issue? i.e. by simply skipping the calculations if length(acalc) = 1?

I tried simply stating if length(acalc) > 1 before this section of code, but that didn't seem to work.

Many thanks,

Tom

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Matt J 2013-12-3

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/108445-skipping-calculations-using-if#answer_117111

在 MATLAB Online 中打开

No, if length(acalc)=1, the code you've shown would never be executed. For example, running the following will not result in anything displayed.

acalc=10;
for j = 1:(length(acalc)-1)
   disp 'Executing'
end

4 个评论
显示 2更早的评论隐藏 2更早的评论

Tom 2013-12-3

I thought that was the problem. But the problem is that most of the time (that section of the code is within a loop of its own) acalc consists of 4 or more rows and then everything is fine. What would be the way to skip those calculations for when acalc consists of only 1 row? I thought it would simply be if length(acalc) = 1 ... end. But that didn't work...

Matt J 2013-12-3

编辑：Matt J 2013-12-3

It doesn't look like length(acalc) is the command you should be using if you really intend to measure the number of rows. You should be using size(acalc,1) instead.

请先登录，再进行评论。