Add some debugging code in mconjugate().

src/geometry.c

@@ -279,6 +279,8 @@ void mconjugate( Matrix *To2wout, CONST Matrix *To2win, CONST Matrix *Tincrf,
     mmmul( &t1, Tw2f, Tincrf );
     mmmul( &t2, &t1,         Tf2w );
     mmmul( To2wout, To2win, &t2 );
+    //fprintf(stderr,"mconj dets: Tw2f %g Tincrf %g Tf2w %g To2win %g To2wout %g\n",
+    //	    mdet3(Tw2f),mdet3(Tincrf),mdet3(Tf2w),mdet3(To2win),mdet3(Tf2w),mdet3(To2wout));
   } else {
     mmmul( To2wout, To2win, Tincrf );
   }
@@ -372,6 +374,15 @@ float tfm2iquat( Point *iquat, CONST Matrix *T )
   return (float)sqrtf(1 + trace) * .5f;
 }
 
+/* quickie determinant of 3x3 submatrix */
+float mdet3( CONST Matrix *T )
+{
+  return vlength((CONST Point *)&T->m[0]);
+  Point v01;
+  vcross( &v01, (CONST Point *)&T->m[0], (CONST Point *)&T->m[4] );
+  return vdot( &v01, (CONST Point *)&T->m[8] );
+}
+   
 void tfm2quat( Quat *quat, CONST Matrix *T )
 {
   float ww, xx, yy, zz;  /* i.e. w^2, x^2, etc. */

src/geometry.h

@@ -128,6 +128,9 @@ void mmmul( Matrix *dst, CONST Matrix *a, CONST Matrix *b );
 	 */
 void eucinv( Matrix *dst, CONST Matrix *src );
 
+	/* quickie determinant of 3x3 submatrix */
+float mdet3( CONST Matrix *T );
+
 	/* matrix conjugation: see its use in Gview.C */
 void mconjugate( Matrix *To2wout, CONST Matrix *To2win, CONST Matrix *Tincrf,
 		 CONST Matrix *Tf2w, CONST Matrix *Tw2f,