Cannot identify error in line of code

Hi everyone,

I'm trying to figure out why this line of code is ending up in error whenever I run the code. Is there something small I'm missing maybe? The error is in line 10 by the way.

Thank you!

EDIT: This is the error message:

">> Cnvalues
Index exceeds matrix dimensions.

Error in Cnvalues (line 15)
    Cn12 = ((-CpAOA12(i+1)-CpAOA12(i))./2).*((xvec(i+1))-(xvec(i)));"

[Stephen23]

@Stenila Simon: please edit your question and do both of these things:

1. Show the complete error. This means show us all of the red text. Do NOT use a screenshot: screenshots are useless for us.
2. Show or upload your code. Do NOT use a screenshot: screenshots are useless for us.

Answer 1

[Jan]

You reset sumCn4 in each iteration to 0 and add Cn4. In consequence the result will contain the last element only - if the code does not stop with an error.

The error message tells you, what the problem is. It is required that you show us the message if you want us to help you. We cannot read your mind :-)

I guess, that either CpA0A4 or xvec does not contain 55 elements, such that the index i+1 must fail.

A nicer and faster solution without a loop:

sumCn4 = -2 * sum((CpA0A4(2:end) + CpA0A4(1:end-1)) ./ diff(xvec))

if CpA0A4 and xvec have the same size.

[Stenila Simon]

Thank you so much, I changed my index to 1:53 instead and it worked, as well as putting the "sumCn4=0" outside the loop - thank you both for your help!! :)

Answer 2

[Walter Roberson]

Your initialization of sumCn4 should be before the loop.

Your maximum value for i should be at most min( length(cpAOA4) - 1, xvec - 1) so if those are length 54 then you should have "for i = 1 : 53"