Ejemplo n.º 1
0
// Render on existing image buffer. Resize it if needed
func On(img *image.RGBA, f *data.Slice, fmin, fmax string, arrowSize int, colormap ...color.RGBA) {
	dim := f.NComp()
	switch dim {
	default:
		log.Fatalf("unsupported number of components: %v", dim)
	case 3:
		drawVectors(img, f.Vectors(), arrowSize)
	case 1:
		min, max := extrema(f.Host()[0])
		if fmin != "auto" {
			m, err := strconv.ParseFloat(fmin, 32)
			if err != nil {
				util.Fatal("draw: scale:", err)
			}
			min = float32(m)
		}
		if fmax != "auto" {
			m, err := strconv.ParseFloat(fmax, 32)
			if err != nil {
				util.Fatal("draw: scale:", err)
			}
			max = float32(m)
		}
		if min == max {
			min -= 1
			max += 1 // make it gray instead of black
		}
		drawFloats(img, f.Scalars(), min, max, colormap...)
	}
}
Ejemplo n.º 2
0
func checkNaN(s *data.Slice, name string) {
	h := s.Host()
	for _, h := range h {
		for _, v := range h {
			if math.IsNaN(float64(v)) || math.IsInf(float64(v), 0) {
				util.Fatal("NaN or Inf in", name)
			}
		}
	}
}
Ejemplo n.º 3
0
// Extract real parts, copy them from src to dst.
// In the meanwhile, check if imaginary parts are nearly zero
// and scale the kernel to compensate for unnormalized FFTs.
// scale = 1/N, with N the FFT logical size.
func scaleRealParts(dst, src *data.Slice, scale float32) {
	util.Argument(2*dst.Len() == src.Len())
	util.Argument(dst.NComp() == 1 && src.NComp() == 1)

	srcList := src.Host()[0]
	dstList := dst.Host()[0]

	// Normally, the FFT'ed kernel is purely real because of symmetry,
	// so we only store the real parts...
	maximg := float32(0.)
	for i := 0; i < src.Len()/2; i++ {
		dstList[i] = srcList[2*i] * scale
		if fabs(srcList[2*i+1]) > maximg {
			maximg = fabs(srcList[2*i+1])
		}
	}
	maximg *= float32(math.Sqrt(float64(scale))) // after 1 FFT, normalization is sqrt(N)

	// ...however, we check that the imaginary parts are nearly zero,
	// just to be sure we did not make a mistake during kernel creation.
	if maximg > FFT_IMAG_TOLERANCE {
		log.Fatalf("FFT kernel imaginary part: %v\n", maximg)
	}
}