a problem with a function

1 次查看（过去 30 天）
Rica
Rica 2013-7-23
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

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采纳的回答

David Sanchez
David Sanchez 2013-7-23
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

更多回答（2 个）

Narges M
Narges M 2013-7-23
编辑：Narges M 2013-7-23
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.
Jan
Jan 2013-7-23
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

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