a problem with a function

hi all ! i wrote this simple function

 %
function [ output_args ] = fract_int16( input_args )
if input_args<0
         output_args=round(2^16+input_args*2^15);
else
         output_args=round(input_args*2^15);
end
end

when i use it for negative number for exemple

 %
fract_int16(-0.9133)=35609
fract_int16(0.3481)=11409,
both values ARE TRUE

but when use this function in an array i get a false value

 % 
A=[-0.9133 0.3481]
fract_int16(A)=[-29927 11407]
this is wrong!!

did i make i mistake in writing this function?

thank you all

Answer 1

[David Sanchez]

Try this out:

input_args = [-0.9133 0.3481];
output_args = zeros(size(input_args));
for k=1:length(input_args)
    if input_args(k)<0
             output_args(k)=round(2^16+input_args(k)*2^15);
    else
             output_args(k)=round(input_args(k)*2^15);
    end
end

Answer 2

[Narges M]

Yes, your function is designed to work with one value, and see if that's less than zero or not. So if you want to use it for arrays you need to use a loop either in the function or when calling it. Right now, if any of the array values are less than zero, if would fire TRUE, and then the output would be calculated for the whole array.

Answer 3

[Jan]

And a faster vectorized version:

function output_args = fract_int16(input_args)
output_args= 2^16 * (input_args < 0) + round(input_args * 2^15);
end