[gnumeric] Solver: enhancement to reports.

[Morten Welinder <mortenw src gnome org>]

commit 643504383b03367595c1bb923127e679d28b070f
Author: Morten Welinder <terra gnome org>
Date:   Sun May 17 16:01:34 2015 -0400

    Solver: enhancement to reports.
    
    Semi-secret for now.  This is probably not its final form.

 src/tools/gnm-solver.c |   50 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 50 insertions(+), 0 deletions(-)
---
diff --git a/src/tools/gnm-solver.c b/src/tools/gnm-solver.c
index edb712b..4bf74c3 100644
--- a/src/tools/gnm-solver.c
+++ b/src/tools/gnm-solver.c
@@ -1667,6 +1667,56 @@ gnm_solver_create_report (GnmSolver *solver, const char *name)
 
        /* ---------------------------------------- */
 
+       if (gnm_solver_has_solution (solver) &&
+           gnm_debug_flag ("solver-sensitivity")) {
+               unsigned ui;
+               const int N = 500;
+               gnm_float const *xs0 = solver->result->solution;
+
+               if (gnm_solver_debug ()) {
+                       gnm_float *g = gnm_solver_compute_gradient (solver, xs0);
+                       print_vector ("Computed gradient", g, solver->input_cells->len);
+                       g_free (g);
+               }
+
+               gnm_solver_set_vars (solver, xs0);
+
+               for (ui = 0; ui < solver->input_cells->len; ui++) {
+                       char *txt;
+                       int i, j;
+                       gnm_float x0, y0, x, y;
+                       GnmCell *cell = g_ptr_array_index (solver->input_cells, ui);
+
+                       R++;
+                       txt = g_strdup_printf (_("Neighborhood for %s\n"),
+                                              cell_name (cell));
+                       ADD_HEADER (txt);
+                       g_free (txt);
+
+                       x0 = xs0[ui];
+                       y0 = solver->result->value;
+
+                       x = x0;
+                       for (i = 0; i < N; i++)
+                               for (j = 0; j < 10; j++)
+                                       x = nextafter (x, gnm_ninf);
+
+                       for (i = -N; i <= +N; i++) {
+                               gnm_solver_set_var (solver, ui, x);
+                               y = gnm_solver_get_target_value (solver);
+
+                               add_value_or_special (dao, 1, R, x - x0);
+                               add_value_or_special (dao, 2, R, y - y0);
+                               R++;
+
+                               for (j = 0; j < 10; j++)
+                                       x = nextafter (x, gnm_pinf);
+                       }
+                       gnm_solver_set_var (solver, ui, x0);
+               }
+       }
+
+       /* ---------------------------------------- */
        dao_redraw_respan (dao);
 
        dao_free (dao);