Index: trunk/psLib/test/math/tap_psPolynomialUtils_Derivatives.c
===================================================================
--- trunk/psLib/test/math/tap_psPolynomialUtils_Derivatives.c	(revision 10597)
+++ trunk/psLib/test/math/tap_psPolynomialUtils_Derivatives.c	(revision 10605)
@@ -8,5 +8,5 @@
 int main (void)
 {
-    plan_tests(48);
+    plan_tests(72);
 
     diag("psPolynomial2D Derivative tests");
@@ -109,4 +109,51 @@
     }
 
+    // test psPolynomial2D_dX (inPlace: supplied output == supplied input)
+    {
+        psMemId id = psMemGetId();
+
+        diag ("test psPolynomial2D_dX (supplied output)");
+
+        psPolynomial2D *poly = psPolynomial2DAlloc(PS_POLYNOMIAL_ORD, 2, 2);
+        ok(poly != NULL, "psPolynomial2D successfully allocated");
+        skip_start(poly == NULL, 5, "Skipping tests because psPolynomial2DAlloc() failed");
+
+        // build sample polynomial (upper-left elements only)
+        // z = 5 + 2x + 3y - 3x^2 + 4xy - 2y^2
+        // dz/dx = 2 - 6x + 4y
+        poly->coeff[0][0] = 5.0;
+        poly->coeff[1][0] = 2.0;
+        poly->coeff[0][1] = 3.0;
+        poly->coeff[2][0] = -3.0;
+        poly->coeff[1][1] = 4.0;
+        poly->coeff[0][2] = -2.0;
+
+        // mask remaining elements
+        poly->mask[2][1] = 1;
+        poly->mask[1][2] = 1;
+        poly->mask[2][2] = 1;
+
+        poly = psPolynomial2D_dX (poly, poly);
+
+        ok(poly->nX == 1, "new x order is %d", poly->nX);
+        ok(poly->nY == 2, "new y order is %d", poly->nY);
+
+        ok_float(poly->coeff[0][0], +2.0, "x^0 y^0 coeff is %f", poly->coeff[0][0]);
+        ok_float(poly->coeff[1][0], -6.0, "x^1 y^0 coeff is %f", poly->coeff[1][0]);
+        ok_float(poly->coeff[0][1], +4.0, "x^0 y^1 coeff is %f", poly->coeff[0][1]);
+
+        ok(!poly->mask[0][0], "x^0 y^0 coeff is unmasked");
+        ok(!poly->mask[1][0], "x^1 y^0 coeff is unmasked");
+        ok(!poly->mask[0][1], "x^0 y^1 coeff is unmasked");
+
+        ok(poly->mask[1][1], "x^1 y^1 coeff is masked");
+        ok(poly->mask[1][2], "x^1 y^2 coeff is masked");
+
+        psFree (poly);
+
+        skip_end();
+        ok(!psMemCheckLeaks (id, NULL, NULL, false), "no memory leaks");
+    }
+
     // test psPolynomial2D_dY (no supplied output)
     {
@@ -136,6 +183,6 @@
         psPolynomial2D *dY = psPolynomial2D_dY (NULL, poly);
 
-        ok(dY->nX == 1, "new x order is %d", dY->nX);
-        ok(dY->nY == 2, "new y order is %d", dY->nY);
+        ok(dY->nX == 2, "new x order is %d", dY->nX);
+        ok(dY->nY == 1, "new y order is %d", dY->nY);
 
         ok_float(dY->coeff[0][0], +3.0, "x^0 y^0 coeff is %f", dY->coeff[0][0]);
@@ -185,6 +232,6 @@
         psPolynomial2D_dY (dY, poly);
 
-        ok(dY->nX == 1, "new x order is %d", dY->nX);
-        ok(dY->nY == 2, "new y order is %d", dY->nY);
+        ok(dY->nX == 2, "new x order is %d", dY->nX);
+        ok(dY->nY == 1, "new y order is %d", dY->nY);
 
         ok_float(dY->coeff[0][0], +3.0, "x^0 y^0 coeff is %f", dY->coeff[0][0]);
@@ -206,4 +253,51 @@
     }
 
+    // test psPolynomial2D_dY (supplied output)
+    {
+        psMemId id = psMemGetId();
+
+        diag ("test psPolynomial2D_dY (supplied output)");
+
+        psPolynomial2D *poly = psPolynomial2DAlloc(PS_POLYNOMIAL_ORD, 2, 2);
+        ok(poly != NULL, "psPolynomial2D successfully allocated");
+        skip_start(poly == NULL, 5, "Skipping tests because psPolynomial2DAlloc() failed");
+
+        // build sample polynomial (upper-left elements only)
+        // z = 5 + 2x + 3y - 3x^2 + 4xy - 2y^2
+        // dz/dy = 3 + 4x - 4y
+        poly->coeff[0][0] = 5.0;
+        poly->coeff[1][0] = 2.0;
+        poly->coeff[0][1] = 3.0;
+        poly->coeff[2][0] = -3.0;
+        poly->coeff[1][1] = 4.0;
+        poly->coeff[0][2] = -2.0;
+
+        // mask remaining elements
+        poly->mask[2][1] = 1;
+        poly->mask[1][2] = 1;
+        poly->mask[2][2] = 1;
+
+        poly = psPolynomial2D_dY (poly, poly);
+
+        ok(poly->nX == 2, "new x order is %d", poly->nX);
+        ok(poly->nY == 1, "new y order is %d", poly->nY);
+
+        ok_float(poly->coeff[0][0], +3.0, "x^0 y^0 coeff is %f", poly->coeff[0][0]);
+        ok_float(poly->coeff[1][0], +4.0, "x^1 y^0 coeff is %f", poly->coeff[1][0]);
+        ok_float(poly->coeff[0][1], -4.0, "x^0 y^1 coeff is %f", poly->coeff[0][1]);
+
+        ok(!poly->mask[0][0], "x^0 y^0 coeff is unmasked");
+        ok(!poly->mask[1][0], "x^1 y^0 coeff is unmasked");
+        ok(!poly->mask[0][1], "x^0 y^1 coeff is unmasked");
+
+        ok(poly->mask[1][1], "x^1 y^1 coeff is masked");
+        ok(poly->mask[1][2], "x^1 y^2 coeff is masked");
+
+        psFree (poly);
+
+        skip_end();
+        ok(!psMemCheckLeaks (id, NULL, NULL, false), "no memory leaks");
+    }
+
     return exit_status();
 }