comparison src/fftw-3.3.3/dft/zero.c @ 10:37bf6b4a2645

Add FFTW3

+/*
+ * Copyright (c) 2003, 2007-11 Matteo Frigo
+ * Copyright (c) 2003, 2007-11 Massachusetts Institute of Technology
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+
+#include "dft.h"
+
+/* fill a complex array with zeros. */
+static void recur(const iodim *dims, int rnk, R *ri, R *ii)
+{
+     if (rnk == RNK_MINFTY)
+          return;
+     else if (rnk == 0)
+          ri[0] = ii[0] = K(0.0);
+     else if (rnk > 0) {
+          INT i, n = dims[0].n;
+          INT is = dims[0].is;
+
+	  if (rnk == 1) {
+	       /* this case is redundant but faster */
+	       for (i = 0; i < n; ++i)
+		    ri[i * is] = ii[i * is] = K(0.0);
+	  } else {
+	       for (i = 0; i < n; ++i)
+		    recur(dims + 1, rnk - 1, ri + i * is, ii + i * is);
+	  }
+     }
+}
+
+
+void X(dft_zerotens)(tensor *sz, R *ri, R *ii)
+{
+     recur(sz->dims, sz->rnk, ri, ii);
+}