Subscript indices must either be real positive integers or logicals.

I was trying to code modified euler cauchy method for solving ODE-IVP. I am getting the following error,

Subscript indices must either be real positive integers or logicals.

When I removes 0.5*h_int from the 4th equation, this error gets solved. How to fix this? I need to implement same algorithm.

for n=1:N_samples-1 x_tilde=cauchy(:,n)+(h_int/2)*my_fun(time(n),cauchy(:,n)); cauchy(:,n+1)=cauchy(:,n)+h_int*my_fun(time(n+0.5*h_int),x_tilde); X0=cauchy(:,n+1); end

Answer 1

[Image Analyst]

It's throughly explained in the FAQ: https://matlab.wikia.com/wiki/FAQ#How_do_I_fix_the_error_.22Subscript_indices_must_either_be_real_positive_integers_or_logicals..22.3F

In addition, see this tuotrial: http://www.mathworks.com/matlabcentral/answers/13205#answer_18099