Delaying the input of a System

Say my input is a sine wave something like this :

Fs = 1000;
t = 0.001:1/Fs:1.005;
fm= 1;
 u = sin(2*pi*fm*t)'

Now i need my input to start from 6th sample instead of 1st. u (1:5) =0; But when i run the code, my 6th sample is found to be u(6)= 0.0377 but i need my 6th sample to be 0.0063 which is u(1) before initialized to zero.

I mean i m not getting my sine wave to start at 6 th sample.. as the first 5 samples are not considered in my code (assigned to zero ).

Could any one help me with this ?

Answer 1

[Mischa Kim]

Sai, use

 u = sin(2*pi*fm*(t-t(6)))';
 u(1:5) = 0;

[Sai kasyap]

Hey , if my input is randn instead of sine ! how to do it then ?