1 files changed, 23 insertions, 0 deletions

diff --git a/packages/sundials/src/helpers.c b/packages/sundials/src/helpers.c
index 3e1a9a8..d51310c 100644
--- a/packages/sundials/src/helpers.c
+++ b/packages/sundials/src/helpers.c
@@ -69,3 +69,26 @@ int Jac(realtype t, N_Vector y, N_Vector fy, SUNMatrix J,
 
   return 0;                                   /* return with success */
 }
+
+
+/* check the computed solution */
+int check_ans(N_Vector y, realtype t, realtype rtol, realtype atol)
+{
+  int      passfail=0;     /* answer pass (0) or fail (1) flag     */  
+  realtype ans, err, ewt;  /* answer data, error, and error weight */
+  realtype ONE=RCONST(1.0);
+
+  /* compute solution error */
+  ans  = atan(t);
+  ewt = ONE / (rtol * SUNRabs(ans) + atol);
+  err = ewt * SUNRabs(NV_Ith_S(y,0) - ans);
+
+  /* is the solution within the tolerances? */
+  passfail = (err < ONE) ? 0 : 1; 
+
+  if (passfail) {
+    fprintf(stdout, "\nSUNDIALS_WARNING: check_ans error=%g \n\n", err);
+  }
+
+  return(passfail);
+}