Subscripted assignment dimension mismatch
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Below is my code. When my program tries to calculate D, it gives me the error as stated in the title. the Varibles N, Eab, den, and V all produce a matrix of 1x47 values. I have tried removing the dot (.) from the equation's multiplication and divisons, but I still get errors (inner matrix dimnesions must agree). Any help is appreciated. Thank you.
row = 0;
col = 0;
for row = 1:1:420
for col = 1:1:420
N = No - No.*exp(-linavg*d);
Eab = E.*(lin./linavg);
D(row,col) = (N.*Eab)./(den.*V);
No = N*exp(-linavg*d);
end
col = col +1;
end
row = row+ 1;
3 个评论
per isakson
2020-3-4
编辑：per isakson
2020-3-4
What are the statemets
row = 0;
col = 0;
col = col +1;
row = row+ 1;
supposed to do?
Pre-allocate D before entering the for-loops
D = nan(420,420);
Left hand side of
D(row,col) = (N.*Eab)./(den.*V);
is a scalar and the right hand side is a 1x47 vector. That doesn't agree. What do you want to achieve with this statement?
Kira Bruce
2020-3-4
Aquatris
2020-3-4
编辑：per isakson
2020-3-4
First of you do not need to specify col = col+1. When you define for col = 1:100, the for loop will increment the col variable every iteration
Secondly, do you want D to be a 3D matrix? If so,
D(row,col,1:47) = (N.*Eab)./(den.*V);
采纳的回答
per isakson
2020-3-5
编辑：per isakson
2020-3-5
See for loop to repeat specified number of times and note especially, "[...]Avoid assigning a value to the index variable within the loop statements. The for statement overrides any changes made to index within the loop." Thus, inside the loop the for-statement totally controls the value of the index.
Try
D = nan( 47, 420, 420 ); % Pre-allocate D before entering the for-loops
for row = 1:1:420
for col = 1:1:420
N = No - No.*exp(-linavg*d);
Eab = E.*(lin./linavg);
D( :, row, col ) = (N.*Eab)./(den.*V);
No = N*exp(-linavg*d);
end
end
By putting the result of the inner loop in the first dimension of D the 47 values are adjacent in memory, which gives a (small) performance gain.
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