localdef.h Source File

00001 //
00002 // localdef.h
00003 //
00004 // Copyright (C) 1996 Limit Point Systems, Inc.
00005 //
00006 // Author: Edward Seidl <seidl@janed.com>
00007 // Maintainer: LPS
00008 //
00009 // This file is part of the SC Toolkit.
00010 //
00011 // The SC Toolkit is free software; you can redistribute it and/or modify
00012 // it under the terms of the GNU Library General Public License as published by
00013 // the Free Software Foundation; either version 2, or (at your option)
00014 // any later version.
00015 //
00016 // The SC Toolkit is distributed in the hope that it will be useful,
00017 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00018 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00019 // GNU Library General Public License for more details.
00020 //
00021 // You should have received a copy of the GNU Library General Public License
00022 // along with the SC Toolkit; see the file COPYING.LIB.  If not, write to
00023 // the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
00024 //
00025 // The U.S. Government is granted a limited license as per AL 91-7.
00026 //
00027 
00028 // some inline functions for dealing with 3 dimensional vectors
00029 
00030 #ifndef _localdef_h
00031 #define _localdef_h
00032 
00033 #include <math.h>
00034 
00035 namespace sc {
00036 
00037 static const double pi=3.14159265358979323846;
00038 static const double pih=1.57079632679489661923;
00039 static const double tpi=2.0*pi;
00040 
00041 static const double bohr = 0.52917706;
00042 
00043 // /////////////////////////////////////////////////////////
00044 
00045 static inline void
00046 delta(double u[], const double a[], const double b[])
00047 {
00048   u[0]=a[0]-b[0];
00049   u[1]=a[1]-b[1];
00050   u[2]=a[2]-b[2];
00051 }
00052 
00053 // /////////////////////////////////////////////////////////
00054 
00055 // returns the distance between two points
00056 static inline double
00057 dist(const double a[], const double b[])
00058 {
00059   double x,y,z;
00060   return (sqrt((x=a[0]-b[0])*x + (y=a[1]-b[1])*y + (z=a[2]-b[2])*z));
00061 }
00062 
00063 // /////////////////////////////////////////////////////////
00064 
00065 // given sin(x) returns cos(x) 
00066 static inline double
00067 s2(double x)
00068 {
00069   double tmp = 1.0 - x*x;
00070   if (tmp < 0.0) tmp = 0.0;
00071   return sqrt(tmp);
00072 }
00073 
00074 // /////////////////////////////////////////////////////////
00075 
00076 // returns the dot product for two vectors
00077 static inline double
00078 scalar(const double a[], const double b[])
00079 {
00080   double x = a[0]*b[0];
00081   double x1 = a[1]*b[1];
00082   x += a[2]*b[2];
00083   return x+x1;
00084 }
00085 
00086 // /////////////////////////////////////////////////////////
00087 
00088 // given vectors a and b, returns a unit vector directed along the difference
00089 // of the two vectors
00090 static inline void
00091 norm(double u[], const double a[], const double b[])
00092 {
00093   delta(u,a,b);
00094   double x = 1.0/sqrt(scalar(u,u));
00095   u[0] *= x; u[1] *= x; u[2] *= x;
00096 }
00097 
00098 // /////////////////////////////////////////////////////////
00099 
00100 // given two vectors, returns the normalized cross product of those vectors
00101 static inline void
00102 normal(const double a[], const double b[], double w[])
00103 {
00104   w[0] = a[1]*b[2]-a[2]*b[1];
00105   w[1] = a[2]*b[0]-a[0]*b[2];
00106   w[2] = a[0]*b[1]-a[1]*b[0];
00107   double x = 1.0/sqrt(scalar(w,w));
00108   w[0] *= x; w[1] *= x; w[2] *= x;
00109 }
00110 
00111 }
00112 
00113 #endif
00114 
00115 // Local Variables:
00116 // mode: c++
00117 // c-file-style: "ETS"
00118 // End: