X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=moebius2.git;a=blobdiff_plain;f=common.c;h=3b036aaa29f54508a5708a1965347734dc5cfa5e;hp=62b981efa930fd19bbb3eab3bb94dd0ba0d14d69;hb=c9f085069bc4e555689dffedbfa08af250772f2a;hpb=97ef96dd318b684d829ac950403582788df427d8

diff --git a/common.c b/common.c
index 62b981e..3b036aa 100644
--- a/common.c
+++ b/common.c
@@ -15,6 +15,14 @@ double magnD(const double pq[D3]) {
   return gsl_blas_dnrm2(&v);
 }
 
+double magnD2(const double pq[D3]) {
+  int k;
+  double d2= 0;
+  
+  K d2= ffsqa(pq[k], d2);
+  return d2;
+}
+
 double hypotD(const double p[D3], const double q[D3]) {
   int k;
   double pq[D3];
@@ -43,6 +51,18 @@ void xprod(double r[D3], const double a[D3], const double b[D3]) {
   r[2]= a[0]*b[1] - a[1]*b[0];
 }
 
+void normalise(double v[D3], double one, double absepsilon) {
+  int k;
+  double multby= one/(magnD(v) + absepsilon);
+  K v[k] *= multby;
+}
+
+void xprod_norm(double r[D3], const double a[D3], const double b[D3],
+		double one, double absepsilon) {
+  xprod(r,a,b);
+  normalise(r, absepsilon, one);
+}
+
 double dotprod(const double a[D3], const double b[D3]) {
   int k;
   double result= 0;
@@ -62,4 +82,4 @@ void gsldie(int l, const char *what, int status) {
 
 void diee(const char *what) { perror(what); exit(16); }
 void fail(const char *emsg) { fputs(emsg,stderr); exit(12); }
-void flushoutput(void) { if (fflush(stdout)||ferror(stdout)) diee("stdout"); }
+void flushoutput(void) { if (ferror(stdout)||fflush(stdout)) diee("stdout"); }