// Assumes that f is no smaller than x.
func copyRealToChannel(f *rimg64.Multi, p int, x *fftw.Array2) {
for u := 0; u < f.Width; u++ {
for v := 0; v < f.Height; v++ {
f.Set(u, v, p, real(x.At(u, v)))
}
}
}
// Assumes that f is no smaller than x.
func copyRealTo(f *rimg64.Image, x *fftw.Array2) {
for u := 0; u < f.Width; u++ {
for v := 0; v < f.Height; v++ {
f.Set(u, v, real(x.At(u, v)))
}
}
}
// ai <- k ai
func scale(k complex128, c *fftw.Array2) {
m, n := c.Dims()
for i := 0; i < m; i++ {
for j := 0; j < n; j++ {
c.Set(i, j, k*c.At(i, j))
}
}
}
// ci <- k conj(ai) bi
func scaleMul(c *fftw.Array2, k complex128, a, b *fftw.Array2) {
m, n := a.Dims()
for i := 0; i < m; i++ {
for j := 0; j < n; j++ {
ax := cmplx.Conj(a.At(i, j))
bx := b.At(i, j)
c.Set(i, j, k*ax*bx)
}
}
}
// ci <- ci + conj(ai) bi
func addMul(c *fftw.Array2, a, b *fftw.Array2) {
m, n := a.Dims()
for i := 0; i < m; i++ {
for j := 0; j < n; j++ {
ax := cmplx.Conj(a.At(i, j))
bx := b.At(i, j)
cx := c.At(i, j)
c.Set(i, j, cx+ax*bx)
}
}
}