Building Sparse Matrix with Integer Errors

I am trying ot build a sparse matrix, but I keep receiving the error: Subscript indices must either be real positive integers or logicals.

My eps are all real positive integers and my Phi_1 values are positive values to the smallest is 3*10^(-4). Does this not count?

[John D'Errico]

To avoid your next error, spdiags is spelt spdiags, not spdiangs.

[EB]

Haha, thank you.

Answer 1

[Matt J]

My eps are all real positive integers and my Phi_1 values are positive values to the smallest is 3*10^(-4). Does this not count?

3*10^(-4) definitely does not count as a positive integer (because it is not an integer). However, the error you are getting has nothing to do with the values of eps or Pi_1. It has to do with xs. In this line,

    F = ffunc(xs)';

ffunc is a matrix, not function, and so xs are expected to be indices (positive integers), not function inputs.