Why I have the error message : Subscript indices must either be real positive integers or logicals.

Hi, can someone explain me this realy weird stuff that hapend... Why on the first programe, line 5 (erf=erf(x)) is working, but not line 10 (erf5=erf(x5))

I also have a ''test program' where the same code is working...

Programe:

clear all
clc
x=linspace(0,2,50);
p7=2./sqrt(pi).*(x-(x.^3./3)+(x.^5./10)-(x.^7./42));
erf=erf(x);
figure(1)
plot (x,p7,'r',x,erf,'g')
legend('approximation','erf','location','northwest')
x5=[1/2 1/4 1/8 1/16 1/32];
erf5=erf(x5);

''test program'' :

clear all 
clc
x=linspace(0,2,50);
erf1=erf(x);
x2=2;
erf2=erf(x2);
x3=[2 3];
erf3=erf(x3);
x4=[1 2 3 4 5 6 7 8 9];
erf4=erf(x4);
x5=[1/2 1/4 1/8 1/16 1/32];
erf5=erf(x5);

Answer 1

[Niels]

its pretty simple. In your testprogramm you saved erf(x1) in erf1. in your programm you overwrite erf:

erf=erf(x)

so that erf is no longer a function (handle)

change that line to

erf1=erf(x)
% or
erf0=erf(x)

and your problem should be solved

[Cookie]

Wow! that simple! Thank you!!!

Answer 2

[Image Analyst]

This is a FAQ. Read up on it here: http://matlab.wikia.com/wiki/FAQ#How_do_I_fix_the_error_.22Subscript_indices_must_either_be_real_positive_integers_or_logicals..22.3F