0 个投票

for i=1:n-1
for j=1:n-1
for r=1:332
if i + r > 333
data(i+r,:)=0;
*else if i-r = < 0
data(i-r,:)=0;*
else if j+r > 333
data(:,j+r)=0;
else if j-r = < 0
data(:,j-r)=0;
end
end
end
end
end
end
end
Please tell me how I can correct the error at i-r = < 0

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 采纳的回答

Walter Roberson
Walter Roberson 2012-2-4

1 个投票

Change the '= <' to '<=' (without the apostrophes.)
http://www.mathworks.com/help/techdoc/ref/le.html

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Amit
Amit 2012-2-4
i do the correction, but there is one more error, plz tell me how i can correct it
??? Subscript indices must either be real positive integers or logicals.
data(i-r,:)=0;
Walter Roberson
Walter Roberson 2012-2-4
Your code has (after correction to <= )
else if i-r <= 0
data(i-r,:)=0;
But if i-r <= 0 as found by the "if" test, then i-r is 0 or negative, and you are then trying to use that 0 or negative value as a subscript of "data".
Perhaps you wanted to test if i-r > 0 ?
You have the same problem with all of your "if" tests: you check for something that would be out of range, and when you find it, you use the out-of-range value!
Amit
Amit 2012-2-4
thanks, yet there is one problem doing this
else if i-r > 0
data(i-r,:);
??? Attempted to access data(0,1); index must be a positive
integer or logical.
Walter Roberson
Walter Roberson 2012-2-4
That would happen if your test was
elseif i-r >= 0
but that cannot happen if your test is
elseif i-r > 0
Amit
Amit 2012-2-4
??? Attempted to access data(0,1); index must be a positive
integer or logical.
Error in ==> file at 30
s=s+data(i+r,j)+data(i-r,j)
Walter Roberson
Walter Roberson 2012-2-4
That involves code you have not posted above. I would need to see the updated code.
Amit
Amit 2012-2-4
The whole code look like this
n=length(data(1,:));
for i=1:n-1
for j=1:n-1
for r=1:332
if i + r > 333
data(i+r,:)=0;
else if i-r > 0
data(i-r,:);
else if j+r > 333
data(:,j+r)=0;
else if j-r > 0
data(:,j-r);
end
end
end
end
s=s+data(i+r,j)+data(i-r,j)
end
end
end
Walter Roberson
Walter Roberson 2012-2-4
Your line s=s+data(i+r,j)+data(i-r,j) is outside of any of your "if" tests, so it is going to always be executed. It will cause a problem if i-r is 0 or negative.
Amit
Amit 2012-2-4
Thanks Walter

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更多回答（1 个）

Jan
Jan 2012-2-4

0 个投票

Do you really have a space between the = and the < ? If so, remove it.
Please add the error message. Otherwise we have to guess, what your problem might be.

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Amit
Amit 2012-2-4
Error: File: file.m Line: 19 Column: 33
The expression to the left of the equals sign is not a
valid target for an assignment.

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