how to multiply each row in a column by different numbers

say, a file consists of a single column with 10000 rows

 load file.txt
 a = file;                       
 k=1:10000;                         
 s = a(k,1).*cosd(3.6*k); 

 k=0:10000;                       
 plot(k,s)                       
 xlabel('k');

it does work at all, could anyone help?

[Image Analyst]

Do you know how to use the debugger to step though your code? This would be easily solved if you did that.

[Passband Modulation]

it says:

Error in ==> Untitled3 at 5 s = a(k,1)-56.97*cosd(3.6*k)-31.98*sind(3.6*k);

how to fix it, i really have no any idea.

Answer 1

[John]

Try this if a is a column vector:

load file.txt

a = file;

k = [1:size(a,1)]';

s = a.*(cosd(3.6*k));

plot(k,s)

xlabel('k');

Alternatively, k can be any column vector you wish to perform element-by-element multiplication with a. Just make sure a and k are of the same size.

[Passband Modulation]

a and k are of the same size.

and thank you for your kind reply!!