Can anybody drop some hints on how to get this working? I have tried testing it on some data (a combination of two sine waves with different frequencies) but I only ever get one “spike” in the output. And this is always in the zeroth element of the array, which suggests something is a bit wrong? My attempt at using the script is below:

y=[];output=[];

for(x=0;x<1000;x++)
{
y[x]=2*Math.cos(Math.PI*2*x)+Math.cos(Math.PI*4*x);
}

//alert(y);
var len = y.length;
var output = new Array();
for( var k=0; k < len; k++ ) {
var real = 0;
var imag = 0;
for( var n=0; n < len; n++ ) {
real += y[n]*Math.cos(-2*Math.PI*k*n/len);
imag += y[n]*Math.sin(-2*Math.PI*k*n/len);
}

output.push( [ real, imag ] ) }

alert(output);

Thank you

Matt