define an array in equation

pi2=2*pi;
k=14e12;
fc=55e6;
tp=5e-6;
D=-tp/2:0.1e-6:tp/2;
tau=(D);

I have an array element tau.

I need to put this into an equation. so, i wrote the code as

Stx(tau)=(exp(1j*pi2*((fc*tau)+((k*(tau^2))/2))));

but it showed me error:

 Subscript indices must either be real positive integers or logicals.

Error in ==> factorized1 at 37
Stx(tau(D))=floor(exp(1j*pi2*((fc*tau)+((k*(tau.^2))/2))));

so how can i define it?

Answer 1

[Walter Roberson]

You cannot define "equations" in MATLAB except in the symbolic toolbox.

Try

Stx= @(tau) (exp(1j*pi2*((fc*tau)+((k*(tau^2))/2))));

and then Stx would become a function that you could pass tau to and get a result from.

Answer 2

[Youssef Khmou]

hi, try directly :

 Stx=(exp(1j*pi2*((fc*tau)+((k*(tau.^2))/2))));

 plot(real(Stx))