include TabularFunction class

2021-05-04 00:24:12 -04:00
parent 9137c579ba
commit 4f9f87c8ab
2 changed files with 347 additions and 0 deletions
--- a/src/tabular_function.h
+++ b/src/tabular_function.h
@ -0,0 +1,68 @@
+/* -*- c++ -*- ----------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   https://lammps.sandia.gov/, Sandia National Laboratories
+   Steve Plimpton, sjplimp@sandia.gov
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+#ifndef LMP_TABULAR_FUNCTION_H
+#define LMP_TABULAR_FUNCTION_H
+
+namespace LAMMPS_NS {
+class TabularFunction {
+ public:
+  TabularFunction();
+  TabularFunction(int, double, double);
+  virtual ~TabularFunction();
+
+  void set_values(int, double, double, double *);
+  void set_values(int, double, double, double *, double);
+
+ private:
+  int size;
+  double xmin, xmax, xmaxsq, rdx, vmax;
+  double *xs, *ys, *ys1, *ys2, *ys3, *ys4, *ys5, *ys6;
+
+  void set_xrange(double x1, double x2);
+  void reset_size(int);
+  void initialize();
+
+ public:
+  void value(double x, double &y, int ny, double &y1, int ny1)
+  {
+    double ps = (x - xmin) * rdx + 1.0;
+    int ks = ps;
+    if (ks > size - 1) ks = size - 1;
+    ps = ps - ks;
+    if (ps > 1.0) ps = 1.0;
+    if (ny)
+      y = ((ys3[ks - 1] * ps + ys2[ks - 1]) * ps + ys1[ks - 1]) * ps +
+          ys[ks - 1];
+    if (ny1) y1 = (ys6[ks - 1] * ps + ys5[ks - 1]) * ps + ys4[ks - 1];
+  }
+  void value2(double x, double &y, int ny, double &y1, int ny1)
+  {
+    double ps = (x - xmin) * rdx;
+    int ks = ps + 0.5;
+    if (ks > size-1) ks = size-1;
+    if (ks < 0 ) ks = 0;
+    ps = ps - ks;
+    if (ny) y = ((ys3[ks]*ps + ys2[ks])*ps + ys1[ks])*ps + ys[ks];
+    if (ny1) y1 = (ys6[ks]*ps + ys5[ks])*ps + ys4[ks];
+  }
+
+  double get_xmin() const { return xmin; }
+  double get_xmax() const { return xmax; }
+  double get_xmaxsq() const { return xmaxsq; }
+  double get_rdx() const { return rdx; }
+  double get_vmax() { return vmax; }
+};
+}    // namespace LAMMPS_NS
+
+#endif