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Initial data commit

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Ingy döt Net 2023-07-01 11:58:00 -04:00
parent 72d218235f
commit f23f22d71c
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Task/Fast-Fourier-transform/JavaScript/fast-fourier-transform-2.js Normal file
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/*
basic complex number arithmetic from
http://rosettacode.org/wiki/Fast_Fourier_transform#Scala
*/
function Complex(re, im)
{
this.re = re;
this.im = im || 0.0;
}
Complex.prototype.add = function(other, dst)
{
dst.re = this.re + other.re;
dst.im = this.im + other.im;
return dst;
}
Complex.prototype.sub = function(other, dst)
{
dst.re = this.re - other.re;
dst.im = this.im - other.im;
return dst;
}
Complex.prototype.mul = function(other, dst)
{
//cache re in case dst === this
var r = this.re * other.re - this.im * other.im;
dst.im = this.re * other.im + this.im * other.re;
dst.re = r;
return dst;
}
Complex.prototype.cexp = function(dst)
{
var er = Math.exp(this.re);
dst.re = er * Math.cos(this.im);
dst.im = er * Math.sin(this.im);
return dst;
}
Complex.prototype.log = function()
{
/*
although 'It's just a matter of separating out the real and imaginary parts of jw.' is not a helpful quote
the actual formula I found here and the rest was just fiddling / testing and comparing with correct results.
http://cboard.cprogramming.com/c-programming/89116-how-implement-complex-exponential-functions-c.html#post637921
*/
if( !this.re )
console.log(this.im.toString()+'j');
else if( this.im < 0 )
console.log(this.re.toString()+this.im.toString()+'j');
else
console.log(this.re.toString()+'+'+this.im.toString()+'j');
}