Index: /branches/eam_branch_20090208/psLib/src/math/psPolynomialUtils.c
===================================================================
--- /branches/eam_branch_20090208/psLib/src/math/psPolynomialUtils.c	(revision 21481)
+++ /branches/eam_branch_20090208/psLib/src/math/psPolynomialUtils.c	(revision 21482)
@@ -193,11 +193,13 @@
     min.y = yn / det;
 
+    // sigma_xn^2 / xn^2 = sigma_11^2 / C11
+
     // without a supplied error, we calculate the normalized error
-    double detErr2 = 4.0*PS_SQR(poly->coeff[1][1])/6.0 + 8.0*PS_SQR(poly->coeff[0][2]) + 8.0*PS_SQR(poly->coeff[2][0]);
-    double xnErr2 = PS_SQR(poly->coeff[0][1])/6.0 + PS_SQR(poly->coeff[1][1])/6.0 + 2.0*PS_SQR(poly->coeff[1][0]) + 4.0*PS_SQR(poly->coeff[0][2])/6.0;
-    double ynErr2 = PS_SQR(poly->coeff[1][0])/6.0 + PS_SQR(poly->coeff[1][1])/6.0 + 2.0*PS_SQR(poly->coeff[0][1]) + 4.0*PS_SQR(poly->coeff[2][0])/6.0;
-
-    min.xErr = min.x * sqrt(xnErr2 / PS_SQR(xn) + detErr2 / PS_SQR(det));
-    min.yErr = min.y * sqrt(ynErr2 / PS_SQR(yn) + detErr2 / PS_SQR(det));
+    double fdetErr2 = 0.5/PS_SQR(poly->coeff[0][2]) + 0.5/PS_SQR(poly->coeff[2][0]) + 4.0/(6.0*PS_SQR(poly->coeff[1][1]));
+    double fxnErr2 = 1.0/(6.0*PS_SQR(poly->coeff[0][1])) + 1.0/(6.0*PS_SQR(poly->coeff[1][0])) + 1.0/(6.0*PS_SQR(poly->coeff[1][1])) + 0.5/PS_SQR(poly->coeff[0][2]);
+    double fynErr2 = 1.0/(6.0*PS_SQR(poly->coeff[0][1])) + 1.0/(6.0*PS_SQR(poly->coeff[1][0])) + 1.0/(6.0*PS_SQR(poly->coeff[1][1])) + 0.5/PS_SQR(poly->coeff[2][0]);
+
+    min.xErr = fabs(min.x) * sqrt(fxnErr2 + fdetErr2);
+    min.yErr = fabs(min.y) * sqrt(fynErr2 + fdetErr2);
 
     return min;