# Index must be a positive integer or logical.

10 views (last 30 days)
Shashank on 27 Oct 2012
I am getting the following error while running the code:
Attempted to access R1_rk4(17501); index must be a positive integer or logical.
Here's a part of my code where the problem lies:
ie1 = 1 + 0.000035/h1;
R1_te = R1_rk4(ie1);
e_R1 = abs(R1_te - R3_te);
Btw, R1_rk4 is a vector, not a matrix. h1 is a constant (time step in the problem). I am trying to access a specific element of the vector R1_rk4 whose size is (1 x 80000).
Any help in removing the error would be much appreciated.

Azzi Abdelmalek on 27 Oct 2012
Edited: Azzi Abdelmalek on 27 Oct 2012
The problem is in
R1_te = R1_rk4(ie1);
what is the value of ie1
ie1 must be a positive integer or logical.
##### 1 CommentShowHide None
Shashank on 27 Oct 2012
Thanks Azzi. I found out the mistake. The term 0.000035/h1 although turns out to be 17501 when calculating analytically but numerically it will not be an exact integer and that's enough for the indexing routine to complain about it being non-integral.

### More Answers (2)

Image Analyst on 27 Oct 2012
What's the value of ie1? Is it an integer? Maybe you want
integerIndex = max([1 round(ie1)]);
R1_te = R1_rk4(integerIndex);
##### 1 CommentShowHide None
Shashank on 27 Oct 2012
Thanks Image Analyst. I basically need to round off the index to the next possible integer value.

Walter Roberson on 27 Oct 2012
##### 1 CommentShowHide None
Shashank on 27 Oct 2012
Thanks for the link, Walter. I'll check the wiki section before asking a question here.