--- ray/src/common/disk2square.c	2011/02/18 18:41:04	3.2
+++ ray/src/common/disk2square.c	2014/10/23 18:19:14	3.4
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: disk2square.c,v 3.2 2011/02/18 18:41:04 greg Exp $";
+static const char RCSid[] = "$Id: disk2square.c,v 3.4 2014/10/23 18:19:14 greg Exp $";
 #endif
 /*
  *  Disk2Square.c
@@ -11,6 +11,7 @@ static const char RCSid[] = "$Id: disk2square.c,v 3.2 
  * Modified interface slightly (G. Ward)
  */
 
+#define	_USE_MATH_DEFINES
 #include <math.h>
 
 /*
@@ -69,7 +70,7 @@ SDsquare2disk(double ds[2], double seedx, double seedy
                 phi = 0.;
        }
    }
-
+   r *= 0.9999999999999;	/* prophylactic against MS sin()/cos() impl. */
    ds[0] = r * cos(phi);
    ds[1] = r * sin(phi);
 
@@ -101,6 +102,6 @@ SDdisk2square(double sq[2], double diskx, double disky
         a = -(phi - 3*M_PI/2) * b / (M_PI/4);
     }
 
-    sq[0] = (a + 1) * 0.5;
-    sq[1] = (b + 1) * 0.5;
+    sq[0] = a*(0.5/0.9999999999999) + 0.5;
+    sq[1] = b*(0.5/0.9999999999999) + 0.5;
 }