1 files changed, 63 insertions, 0 deletions
diff --git a/demo/curve2.c b/demo/curve2.c
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+++ b/demo/curve2.c
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+/*
+ * Library:  lmfit (Levenberg-Marquardt least squares fitting)
+ *
+ * File:     demo/curve1.c
+ *
+ * Contents: Example for fitting data with error bars:
+ *           fit a data set (x,y+-dy) by a curve f(x;p).
+ *
+ * Author:   Joachim Wuttke <j.wuttke@fz-juelich.de> 2004-2013
+ *
+ * Licence:  see ../COPYING (FreeBSD)
+ *
+ * Homepage: apps.jcns.fz-juelich.de/lmfit
+ */
+
+#include "lmcurve_tyd.h"
+#include <stdio.h>
+
+/* model function: a parabola */
+
+double f( double t, const double *p )
+{
+    return p[0] + p[1]*t + p[2]*t*t;
+}
+
+int main()
+{
+    int n = 3; /* number of parameters in model function f */
+    double par[3] = { 100, 0, -10 }; /* really bad starting value */
+
+    /* data points: a slightly distorted standard parabola */
+    int m = 9;
+    int i;
+    double t[9] = { -4., -3., -2., -1.,  0., 1.,  2.,  3.,  4. };
+    double y[9] = { 16.6, 9.9, 4.4, 1.1, 0., 1.1, 4.2, 9.3, 16.4 };
+    double dy[9] = { 4, 3, 2, 1, 2, 3, 4, 5, 6 };
+
+    lm_control_struct control = lm_control_double;
+    lm_status_struct status;
+    control.verbosity = 1;
+
+    printf( "Fitting ...\n" );
+    /* now the call to lmfit */
+    lmcurve_tyd( n, par, m, t, y, dy, f, &control, &status );
+
+    printf( "Results:\n" );
+    printf( "status after %d function evaluations:\n  %s\n",
+            status.nfev, lm_infmsg[status.outcome] );
+
+    printf("obtained parameters:\n");
+    for ( i = 0; i < n; ++i)
+        printf("  par[%i] = %12g\n", i, par[i]);
+    printf("obtained norm:\n  %12g\n", status.fnorm );
+
+    printf("fitting data as follows:\n");
+    for ( i = 0; i < m; ++i)
+        printf(
+        "  t[%1d]=%2g y=%5.1f+-%4.1f fit=%8.5f residue=%8.4f weighed=%8.4f\n",
+        i, t[i], y[i], dy[i], f(t[i],par), y[i] - f(t[i],par),
+        (y[i] - f(t[i],par))/dy[i] );
+
+    return 0;
+}