babl: in babl_polynomial_approximate_gamma(), verify that x0 >= 0

Now that the previous commit (hopefully) makes us iPhone-proof, we
can add an assertion for this condition.  If we want to replace the
assertions with some sort of bailing, we'll need to replace the rest
of them too anyway.

diff --git a/babl/babl-polynomial.c b/babl/babl-polynomial.c
index c9f195b73bf9b2748cd6e18fd3dfac604804e6be..82f9ce4d3e4d95bd6d04f90311e6827975961936 100644 (file)
--- a/babl/babl-polynomial.c
+++ b/babl/babl-polynomial.c
@@ -516,6 +516,7 @@ babl_polynomial_approximate_gamma (BablPolynomial *poly,
 
   babl_assert (poly != NULL);
   babl_assert (gamma >= 0.0);
+  babl_assert (x0 >= 0.0);
   babl_assert (x0 < x1);
   babl_assert (degree >= BABL_POLYNOMIAL_MIN_DEGREE &&
                degree <= BABL_POLYNOMIAL_MAX_DEGREE);