Matrix dimensions do not agree

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jnovv
jnovv 2015-12-16
评论： jnovv 2015-12-16
Hi everyone,
I am wondering if you can help me with this issue.
I have a differential equation code (dy/dt) that is solved using a solver. At the end I got the the dimension of y to be 2868x11.
There is also another parameter called xinf, with it being defined as
xinf = 1/(1+exp(-(y(:,1)-Vx)/kx))
Vx and kx are both constant. At the end, xinf has the dimension of 1x2868.
The issue takes place when I need to calculate this formula:
Ix = gx*xinf.^3.*y(:,2).*(y(:,1)-Ex)
Ex is a constant.
I receive the error saying that the matrix dimensions do not agree. I tried transposing xinf, and although the code runs, it does not produce the output that is desired.
I was wondering is someone can help me solve this issue? Maybe another way to go about this? As I seem to have reached a dead end.
Many thanks in advance!

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采纳的回答

James Tursa
James Tursa 2015-12-16
My guess is you meant that division in your xinf calculation to be element-wise. E.g., change the / to ./ as follows:
xinf = 1./(1+exp(-(y(:,1)-Vx)/kx))
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jnovv
jnovv 2015-12-16
Thank you for your suggestion! Fixed the problem immediately :)

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更多回答（1 个）

the cyclist
the cyclist 2015-12-16
编辑：the cyclist 2015-12-16
Just stating "it does not produce the output that is desired" is a bit vague. Can you be more specific?
Just a guess, though ... I bet you actually wanted
xinf = 1./(1+exp(-(y(:,1)-Vx)/kx))
rather than
xinf = 1/(1+exp(-(y(:,1)-Vx)/kx))
Notice that I used "./" in place of "/". That also solves your issue with needing to transpose, which gives me a dose of confidence that it was the right operation in the first place.
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jnovv
jnovv 2015-12-16
Thank you very much for your help! The output needs to be in form of a graph that is similar to the data obtained from an experiment, which is quite tricky to explain. But your suggestion did fix it!

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