test.html

<!DOCTYPE html>

<head>
	<title>fft.js</title>
	<script src='lib/real.js'></script>
	<script src='lib/complex.js'></script>
	<script>
	
	function kahanDiff(x, xOffset, xStride, y, yOffset, yStride, n, run) {
		var sum = 0.0, compensation = 0.0
		
		for (var i = 0; i < x.length / run / xStride; i++) {
			for (var j = 0; j < run; j++) {
				var v = Math.abs(x[xOffset + run * xStride * i + j] - y[yOffset + run * yStride * i + j] / n) - compensation
			
				var t = sum + v
			
				compensation = (t - sum) - v
			
				sum = t
				
				if (isNaN(sum)) {
					debugger
				}
			}
		}
		
		return sum
	}
	
	function kahanStrideDiff(x, xOffset, xStride, run) {
		var sum = 0.0, compensation = 0.0
		
		for (var i = 0; i < x.length / run / xStride; i++) {
			for (var j = run; j < run * xStride; j++) {
				var v = Math.abs(x[xOffset + run * xStride * i + j]) - compensation
			
				var t = sum + v
			
				compensation = (t - sum) - v
			
				sum = t
				
				if (isNaN(sum)) {
					debugger
				}
			}
		}
		
		return sum
	}
	
	function kahanOffsetDiff(x, xOffset) {
		var sum = 0.0, compensation = 0.0
		
		for (var i = 0; i < xOffset; i++) {
			var v = Math.abs(x[i]) - compensation
			
			var t = sum + v
			
			compensation = (t - sum) - v
			
			sum = t
				
			if (isNaN(sum)) {
				debugger
			}
		}
		
		return sum
	}
	
	function testComplex(n) {
		var i = new Float64Array(2 * n), o1 = new Float64Array(2 * n), o2 = new Float64Array(2 * n)
		var fft = new FFT.complex(n, false), ifft = new FFT.complex(n, true)
		
		for (var j = 0; j < (2 * n); j++) {
			i[j] = Math.random()
		}
		
		fft.process(o1, 0, 1, i, 0,  1)
		ifft.process(o2, 0, 1, o1, 0, 1)
		
		return kahanDiff(i, 0, 1, o2, 0, 1, n, 2)
	}
	
	function testComplexStride(n) {
		var iStride = ~~(12 * Math.random()) + 1, o1Stride = ~~(16 * Math.random()) + 1, o2Stride = ~~(5 * Math.random()) + 1
		
		var i = new Float64Array(2 * iStride * n), o1 = new Float64Array(2 * o1Stride * n), o2 = new Float64Array(2 * o2Stride * n)
		var fft = new FFT.complex(n, false), ifft = new FFT.complex(n, true)
		
		for (var j = 0; j < n; j++) {
			i[2 * j * iStride + 0] = Math.random()
			i[2 * j * iStride + 1] = Math.random()
		}
		
		fft.process(o1, 0, o1Stride, i, 0, iStride)
		ifft.process(o2, 0, o2Stride, o1, 0, o1Stride)
		
		return [kahanDiff(i, 0, iStride, o2, 0, o2Stride, n, 2), kahanStrideDiff(o2, 0, o2Stride, 2)]
	}
	
	function testRealToComplex(n) {
		var i = new Float64Array(n), o1 = new Float64Array(2 * n), o2 = new Float64Array(2 * n)
		var fft = new FFT.complex(n, false), ifft = new FFT.complex(n, true)
		
		for (var j = 0; j < n; j++) {
			i[j] = Math.random()
		}
		
		fft.simple(o1, i, 'real')
		ifft.simple(o2, o1)
		
		return [kahanDiff(i, 0, 1, o2, 0, 2, n, 1), kahanStrideDiff(o2, 2, 1)]
	}
	
	function testRealToComplexWithOffset(n) {
		var iOffset = ~~(12 * Math.random()), o1Offset = ~~(12 * Math.random()), o2Offset = ~~(12 * Math.random())
		
		var i = new Float64Array(iOffset + n), o1 = new Float64Array(o1Offset + 2 * n), o2 = new Float64Array(o2Offset + 2 * n)
		var fft = new FFT.complex(n, false), ifft = new FFT.complex(n, true)
		
		for (var j = 0; j < n; j++) {
			i[iOffset + j] = Math.random()
		}
		
		fft.process(o1, o1Offset, 1, i, iOffset, 1, 'real')
		ifft.process(o2, o2Offset, 1, o1, o1Offset, 1)
		
		return [kahanDiff(i, 1, o2, 2, n, 1), kahanStrideDiff(o2, 2, 1), kahanOffsetDiff(o1, o1Offset), kahanOffsetDiff(o2, o2Offset)]
	}
	
	
	var count = 0
	for (var i = 2; i < 100; i++) {
		var v = testComplex(i)
		if (isNaN(v) || v > 1e-12) {
			console.log('Complex', i, v), count++
		}
	}
	
	for (var i = 2; i < 100; i++) {
		var v = testComplexStride(i)
		if (isNaN(v[0]) || v[0] > 1e-12 || v[1] > 0) {
			console.log('Complex Strided', i, v), count++
		}
	}
	
	for (var i = 2; i < 100; i++) {
		var v = testRealToComplex(i)
		if (isNaN(v[0]) || isNaN(v[1]) || v[0] > 1e-12 || v[1] > 1e-12) {
			console.log('Real to Complex', i, v), count++
		}
	}
	
	for (var i = 2; i < 100; i++) {
		var v = testRealToComplexWithOffset(i)
		if (isNaN(v[0]) || isNaN(v[1]) || isNaN(v[2]) || isNaN(v[3]) || v[0] > 1e-12 || v[1] > 1e-12 || v[2] > 0 || v[3] > 0) {
			console.log('Real to Complex Offset', i, v), count++
		}
	}
	
	var f0 = new Float64Array(32), r0 = new Float64Array(64), fft = new FFT.complex(32, false); f0[0] = 1, f0[31] = 1
	fft.simple(r0, f0, 'real')
	
	console.log(r0)
	
	console.log("Failcount", count)
	</script>
</head>