Library for f2c (part 2 of 2)

Obtained from: netlib.att.com

1 files changed, 50 insertions, 0 deletions

diff --git a/lib/libF77/pow_zi.c b/lib/libF77/pow_zi.c
new file mode 100644
index 0000000..8dd6006
--- /dev/null
+++ b/lib/libF77/pow_zi.c
@@ -0,0 +1,50 @@
+#include "f2c.h"
+
+#ifdef KR_headers
+VOID pow_zi(p, a, b) 	/* p = a**b  */
+ doublecomplex *p, *a; integer *b;
+#else
+extern void z_div(doublecomplex*, doublecomplex*, doublecomplex*);
+void pow_zi(doublecomplex *p, doublecomplex *a, integer *b) 	/* p = a**b  */
+#endif
+{
+integer n;
+double t;
+doublecomplex x;
+static doublecomplex one = {1.0, 0.0};
+
+n = *b;
+p->r = 1;
+p->i = 0;
+
+if(n == 0)
+	return;
+if(n < 0)
+	{
+	n = -n;
+	z_div(&x, &one, a);
+	}
+else
+	{
+	x.r = a->r;
+	x.i = a->i;
+	}
+
+for( ; ; )
+	{
+	if(n & 01)
+		{
+		t = p->r * x.r - p->i * x.i;
+		p->i = p->r * x.i + p->i * x.r;
+		p->r = t;
+		}
+	if(n >>= 1)
+		{
+		t = x.r * x.r - x.i * x.i;
+		x.i = 2 * x.r * x.i;
+		x.r = t;
+		}
+	else
+		break;
+	}
+}