From 975abbee31abe7f8299c3cc4583f76214f699671 Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Mon, 9 Apr 2018 10:13:44 +0200
Subject: nlsolve: faster abort on divergence

---
 init.c    | 10 +++++-----
 nlsolve.c |  6 +++++-
 nlsolve.h |  2 +-
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/init.c b/init.c
index b1495a6..e90bbb8 100644
--- a/init.c
+++ b/init.c
@@ -284,7 +284,7 @@ int td_solve(TDContext *td, double *coeffs_init[3])
     if (td->solution_branch == 0 || coeffs_init) {
         // direct solve with default (flat space) or user-provided initial guess
         ret = tdi_nlsolve_solve(s->solver, teukolsky_constraint_eval, NULL,
-                                &td->amplitude, s->coeffs);
+                                &td->amplitude, s->coeffs, 0);
         if (ret < 0) {
             tdi_log(&s->logger, 0, "tdi_nlsolve_solve() failed: %d", ret);
             return ret;
@@ -301,11 +301,11 @@ int td_solve(TDContext *td, double *coeffs_init[3])
         int dir;
 
         ret = tdi_nlsolve_solve(s->solver, teukolsky_constraint_eval, NULL,
-                                &a0, s->coeffs);
+                                &a0, s->coeffs, 0);
         if (ret < 0)
             return ret;
         ret = tdi_nlsolve_solve(s->solver, teukolsky_constraint_eval, NULL,
-                               &a1, s->coeffs_tmp);
+                               &a1, s->coeffs_tmp, 0);
         if (ret < 0)
             return ret;
 
@@ -314,7 +314,7 @@ int td_solve(TDContext *td, double *coeffs_init[3])
 
         // obtain solution for a1 in the upper branch
         ret = tdi_nlsolve_solve(s->solver, teukolsky_constraint_eval, NULL,
-                                &a1, s->coeffs);
+                                &a1, s->coeffs, 0);
         if (ret < 0) {
             tdi_log(&s->logger, 0, "Failed to get into the upper branch\n");
             return ret;
@@ -335,7 +335,7 @@ int td_solve(TDContext *td, double *coeffs_init[3])
             tdi_log(&s->logger, 2, "Trying amplitude %g\n", new_amplitude);
             memcpy(s->coeffs_tmp, s->coeffs, sizeof(*s->coeffs) * N);
             ret = tdi_nlsolve_solve(s->solver, teukolsky_constraint_eval, NULL,
-                                    &new_amplitude, s->coeffs_tmp);
+                                    &new_amplitude, s->coeffs_tmp, 1);
             if (ret == -EDOM) {
                 inverse_step = 0.5 * inverse_step;
                 if (fabs(inverse_step) < 1e-2)
diff --git a/nlsolve.c b/nlsolve.c
index 960a8e9..708cd08 100644
--- a/nlsolve.c
+++ b/nlsolve.c
@@ -100,7 +100,7 @@ struct NLSolvePriv {
 };
 
 int tdi_nlsolve_solve(NLSolveContext *ctx, NLEqCallback eq_eval,
-                      NLEqJacobianCallback eq_jac_eval, void *opaque, double *coeffs)
+                      NLEqJacobianCallback eq_jac_eval, void *opaque, double *coeffs, int fast_abort)
 {
     NLSolvePriv *s = ctx->priv;
     int64_t start, totaltime_start;
@@ -209,6 +209,10 @@ int tdi_nlsolve_solve(NLSolveContext *ctx, NLEqCallback eq_eval,
                     it, s->delta[max_idx], ctx->atol);
             ret = 0;
             goto finish;
+        } else if ((fast_abort && fabs(s->delta[max_idx]) > 1e6) ||
+                   s->delta[max_idx] > 1e18) {
+            tdi_log(&ctx->logger, 2, "max(delta) %g, aborting\n", s->delta[max_idx]);
+            return -EDOM;
         }
 
         cblas_daxpy(s->solve_order, 1.0, s->delta, 1, coeffs, 1);
diff --git a/nlsolve.h b/nlsolve.h
index 1d3fae5..f9b69fe 100644
--- a/nlsolve.h
+++ b/nlsolve.h
@@ -101,7 +101,7 @@ void tdi_nlsolve_context_free(NLSolveContext **ctx);
 
 int tdi_nlsolve_solve(NLSolveContext *ctx, NLEqCallback eq_eval,
                       NLEqJacobianCallback eq_jac_eval,
-                      void *opaque, double *coeffs);
+                      void *opaque, double *coeffs, int fast_abort);
 
 void tdi_nlsolve_print_stats(NLSolveContext *ctx);
 
-- 
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