bug fix in grosenbrock gradient (no wonder StoGO etc. were so bad for this functioon)

darcs-hash:20070903192207-c8de0-cef32242ac0bc7308b24d07ae31e2e9e1c6c463a.gz

diff --git a/test/testfuncs.c b/test/testfuncs.c
index cff30974aefa358a3b3d11e7cc18b46ccf2aa91a..3865e20558488f2511013c286107db5cefe9ffd5 100644 (file)
--- a/test/testfuncs.c
+++ b/test/testfuncs.c
@@ -125,7 +125,7 @@ static double grosenbrock_f(int n, const double *x, double *grad, void *data)
          double a = x[i+1] - x[i] * x[i], b = 1 - x[i];
          if (grad) {
               grad[i] += -400 * a * x[i] - 2*b;
-              grad[i+1] = -200 * a;
+              grad[i+1] = 200 * a;
          }
          f += 100 * sqr(a) + sqr(b);
      }