beginning to fold in HOD code with jeremy tinker's approval

c_tools/hod/complex.c

@@ -0,0 +1,125 @@
+/* CAUTION: This is the ANSI C (only) version of the Numerical Recipes
+   utility file complex.c.  Do not confuse this file with the same-named
+   file complex.c that is supplied in the 'misc' subdirectory.
+   *That* file is the one from the book, and contains both ANSI and
+   traditional K&R versions, along with #ifdef macros to select the
+   correct version.  *This* file contains only ANSI C.               */
+
+#include <math.h>
+
+typedef struct FCOMPLEX {float r,i;} fcomplex;
+
+fcomplex Cadd(fcomplex a, fcomplex b)
+{
+	fcomplex c;
+	c.r=a.r+b.r;
+	c.i=a.i+b.i;
+	return c;
+}
+
+fcomplex Csub(fcomplex a, fcomplex b)
+{
+	fcomplex c;
+	c.r=a.r-b.r;
+	c.i=a.i-b.i;
+	return c;
+}
+
+
+fcomplex Cmul(fcomplex a, fcomplex b)
+{
+	fcomplex c;
+	c.r=a.r*b.r-a.i*b.i;
+	c.i=a.i*b.r+a.r*b.i;
+	return c;
+}
+
+fcomplex Complex(float re, float im)
+{
+	fcomplex c;
+	c.r=re;
+	c.i=im;
+	return c;
+}
+
+fcomplex Conjg(fcomplex z)
+{
+	fcomplex c;
+	c.r=z.r;
+	c.i = -z.i;
+	return c;
+}
+
+fcomplex Cdiv(fcomplex a, fcomplex b)
+{
+	fcomplex c;
+	float r,den;
+	if (fabs(b.r) >= fabs(b.i)) {
+		r=b.i/b.r;
+		den=b.r+r*b.i;
+		c.r=(a.r+r*a.i)/den;
+		c.i=(a.i-r*a.r)/den;
+	} else {
+		r=b.r/b.i;
+		den=b.i+r*b.r;
+		c.r=(a.r*r+a.i)/den;
+		c.i=(a.i*r-a.r)/den;
+	}
+	return c;
+}
+
+float Cabs(fcomplex z)
+{
+	float x,y,ans,temp;
+	x=fabs(z.r);
+	y=fabs(z.i);
+	if (x == 0.0)
+		ans=y;
+	else if (y == 0.0)
+		ans=x;
+	else if (x > y) {
+		temp=y/x;
+		ans=x*sqrt(1.0+temp*temp);
+	} else {
+		temp=x/y;
+		ans=y*sqrt(1.0+temp*temp);
+	}
+	return ans;
+}
+
+fcomplex Csqrt(fcomplex z)
+{
+	fcomplex c;
+	float x,y,w,r;
+	if ((z.r == 0.0) && (z.i == 0.0)) {
+		c.r=0.0;
+		c.i=0.0;
+		return c;
+	} else {
+		x=fabs(z.r);
+		y=fabs(z.i);
+		if (x >= y) {
+			r=y/x;
+			w=sqrt(x)*sqrt(0.5*(1.0+sqrt(1.0+r*r)));
+		} else {
+			r=x/y;
+			w=sqrt(y)*sqrt(0.5*(r+sqrt(1.0+r*r)));
+		}
+		if (z.r >= 0.0) {
+			c.r=w;
+			c.i=z.i/(2.0*w);
+		} else {
+			c.i=(z.i >= 0) ? w : -w;
+			c.r=z.i/(2.0*c.i);
+		}
+		return c;
+	}
+}
+
+fcomplex RCmul(float x, fcomplex a)
+{
+	fcomplex c;
+	c.r=x*a.r;
+	c.i=x*a.i;
+	return c;
+}