TP_Utilities.cpp

Go to the documentation of this file.

/* TwoPunctures:  File  "utilities.c"*/
/* these functions have no dependency on the TP parameters */
 
#include <math.h>
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <assert.h>
#include "libtwopunctures/TP_Utilities.h"
 
namespace TP {
namespace Utilities {
 
/*---------------------------------------------------------------------------*/
int *
ivector (long nl, long nh)
/* allocate an int vector with subscript range v[nl..nh] */
{
  int *retval;
 
  retval = new int [(nh-nl+1)];
  if(retval == NULL)
    throw error ("allocation failure in ivector()");
 
  return retval - nl;
}
 
/*---------------------------------------------------------------------------*/
double *
dvector (long nl, long nh)
/* allocate a double vector with subscript range v[nl..nh] */
{
  double *retval;
 
  retval = new double [(nh-nl+1)];
  if(retval == NULL)
    throw error ("allocation failure in dvector()");
 
  return retval - nl;
}
 
/*---------------------------------------------------------------------------*/
int **
imatrix (long nrl, long nrh, long ncl, long nch)
/* allocate a int matrix with subscript range m[nrl..nrh][ncl..nch] */
{
  int **retval;
 
  retval = new int * [(nrh-nrl+1)];
  if(retval == NULL)
    throw error ("allocation failure (1) in imatrix()");
 
  /* get all memory for the matrix in on chunk */
  retval[0] = new int [(nrh-nrl+1)*(nch-ncl+1)];
  if(retval[0] == NULL)
    throw error ("allocation failure (2) in imatrix()");
 
  /* apply column and row offsets */
  retval[0] -= ncl;
  retval -= nrl;
 
  /* slice chunk into rows */
  long width = (nch-ncl+1);
  for(long i = nrl+1 ; i <= nrh ; i++)
    retval[i] = retval[i-1] + width;
  assert(retval[nrh]-retval[nrl] == (nrh-nrl)*width);
 
  return retval;
}
 
/*---------------------------------------------------------------------------*/
double **
dmatrix (long nrl, long nrh, long ncl, long nch)
/* allocate a double matrix with subscript range m[nrl..nrh][ncl..nch] */
{
  double **retval;
 
  retval = new double * [(nrh-nrl+1)];
  if(retval == NULL)
    throw error ("allocation failure (1) in dmatrix()");
 
  /* get all memory for the matrix in on chunk */
  retval[0] = new double [(nrh-nrl+1)*(nch-ncl+1)];
  if(retval[0] == NULL)
    throw error ("allocation failure (2) in dmatrix()");
 
  /* apply column and row offsets */
  retval[0] -= ncl;
  retval -= nrl;
 
  /* slice chunk into rows */
  long width = (nch-ncl+1);
  for(long i = nrl+1 ; i <= nrh ; i++)
    retval[i] = retval[i-1] + width;
  assert(retval[nrh]-retval[nrl] == (nrh-nrl)*width);
 
  return retval;
}
 
/*---------------------------------------------------------------------------*/
double ***
d3tensor (long nrl, long nrh, long ncl, long nch, long ndl, long ndh)
/* allocate a double 3tensor with range t[nrl..nrh][ncl..nch][ndl..ndh] */
{
  double ***retval;
 
  /* get memory for index structures */
  retval = new double ** [(nrh-nrl+1)];
  if(retval == NULL)
    throw error ("allocation failure (1) in d3tensor()");
 
  retval[0] = new double * [(nrh-nrl+1)*(nch-ncl+1)];
  if(retval[0] == NULL)
    throw error ("allocation failure (2) in d3tensor()");
 
  /* get all memory for the tensor in on chunk */
  retval[0][0] = new double [(nrh-nrl+1)*(nch-ncl+1)*(ndh-ndl+1)];
  if(retval[0][0] == NULL)
    throw error ("allocation failure (3) in d3tensor()");
 
  /* apply all offsets */
  retval[0][0] -= ndl;
  retval[0] -= ncl;
  retval -= nrl;
 
  /* slice chunk into rows and columns */
  long width = (nch-ncl+1);
  long depth = (ndh-ndl+1);
  for(long j = ncl+1 ; j <= nch ; j++) { /* first row of columns */
    retval[nrl][j] = retval[nrl][j-1] + depth;
  }
  assert(retval[nrl][nch]-retval[nrl][ncl] == (nch-ncl)*depth);
  for(long i = nrl+1 ; i <= nrh ; i++) {
    retval[i] = retval[i-1] + width;
    retval[i][ncl] = retval[i-1][ncl] + width*depth; /* first cell in column */
    for(long j = ncl+1 ; j <= nch ; j++) {
      retval[i][j] = retval[i][j-1] + depth;
    }
    assert(retval[i][nch]-retval[i][ncl] == (nch-ncl)*depth);
  }
  assert(retval[nrh]-retval[nrl] == (nrh-nrl)*width);
  assert(&retval[nrh][nch][ndh]-&retval[nrl][ncl][ndl] == (nrh-nrl+1)*(nch-ncl+1)*(ndh-ndl+1)-1);
 
  return retval;
}
 
/*--------------------------------------------------------------------------*/
void
free_ivector (int *v, long nl, long nh)
/* free an int vector allocated with ivector() */
{
  free(v+nl);
}
 
/*--------------------------------------------------------------------------*/
void
free_dvector (double *v, long nl, long nh)
/* free an double vector allocated with dvector() */
{
  free(v+nl);
}
 
/*--------------------------------------------------------------------------*/
void
free_imatrix (int **m, long nrl, long nrh, long ncl, long nch)
/* free an int matrix allocated by imatrix() */
{
  free(m[nrl]+ncl);
  free(m+nrl);
}
 
/*--------------------------------------------------------------------------*/
void
free_dmatrix (double **m, long nrl, long nrh, long ncl, long nch)
/* free a double matrix allocated by dmatrix() */
{
  free(m[nrl]+ncl);
  free(m+nrl);
}
 
/*--------------------------------------------------------------------------*/
void
free_d3tensor (double ***t, long nrl, long nrh, long ncl, long nch,
           long ndl, long ndh)
/* free a double d3tensor allocated by d3tensor() */
{
  free(t[nrl][ncl]+ndl);
  free(t[nrl]+ncl);
  free(t+nrl);
}
 
/*--------------------------------------------------------------------------*/
int
minimum2 (int i, int j)
{
  int result = i;
  if (j < result)
    result = j;
  return result;
}
 
/*-------------------------------------------------------------------------*/
int
minimum3 (int i, int j, int k)
{
  int result = i;
  if (j < result)
    result = j;
  if (k < result)
    result = k;
  return result;
}
 
/*--------------------------------------------------------------------------*/
int
maximum2 (int i, int j)
{
  int result = i;
  if (j > result)
    result = j;
  return result;
}
 
/*--------------------------------------------------------------------------*/
int
maximum3 (int i, int j, int k)
{
  int result = i;
  if (j > result)
    result = j;
  if (k > result)
    result = k;
  return result;
}
 
/*--------------------------------------------------------------------------*/
int
pow_int (int mantisse, int exponent)
{
  int i, result = 1;
 
  for (i = 1; i <= exponent; i++)
    result *= mantisse;
 
  return result;
}
 
/*--------------------------------------------------------------------------*/
void
chebft_Zeros (double u[], int n, int inv)
    /* eq. 5.8.7 and 5.8.8 at x = (5.8.4) of 2nd edition C++ NR */
{
  int k, j, isignum;
  double fac, sum, Pion, *c;
 
  c = dvector (0, n);
  Pion = Pi / n;
  if (inv == 0)
  {
    fac = 2.0 / n;
    isignum = 1;
    for (j = 0; j < n; j++)
    {
      sum = 0.0;
      for (k = 0; k < n; k++)
    sum += u[k] * cos (Pion * j * (k + 0.5));
      c[j] = fac * sum * isignum;
      isignum = -isignum;
    }
  }
  else
  {
    for (j = 0; j < n; j++)
    {
      sum = -0.5 * u[0];
      isignum = 1;
      for (k = 0; k < n; k++)
      {
    sum += u[k] * cos (Pion * (j + 0.5) * k) * isignum;
    isignum = -isignum;
      }
      c[j] = sum;
    }
  }
  for (j = 0; j < n; j++)
#if 0
    if (fabs(c[j]) < 5.e-16)
      u[j] = 0.0;
    else
#endif
      u[j] = c[j];
  free_dvector (c, 0, n);
}
 
/* --------------------------------------------------------------------------*/
 
void
chebft_Extremes (double u[], int n, int inv)
    /* eq. 5.8.7 and 5.8.8 at x = (5.8.5) of 2nd edition C++ NR */
{
  int k, j, isignum, N = n - 1;
  double fac, sum, PioN, *c;
 
  c = dvector (0, N);
  PioN = Pi / N;
  if (inv == 0)
  {
    fac = 2.0 / N;
    isignum = 1;
    for (j = 0; j < n; j++)
    {
      sum = 0.5 * (u[0] + u[N] * isignum);
      for (k = 1; k < N; k++)
    sum += u[k] * cos (PioN * j * k);
      c[j] = fac * sum * isignum;
      isignum = -isignum;
    }
    c[N] = 0.5 * c[N];
  }
  else
  {
    for (j = 0; j < n; j++)
    {
      sum = -0.5 * u[0];
      isignum = 1;
      for (k = 0; k < n; k++)
      {
    sum += u[k] * cos (PioN * j * k) * isignum;
    isignum = -isignum;
      }
      c[j] = sum;
    }
  }
  for (j = 0; j < n; j++)
    u[j] = c[j];
  free_dvector (c, 0, N);
}
 
/* --------------------------------------------------------------------------*/
 
void
chder (double *c, double *cder, int n)
{
  int j;
 
  cder[n] = 0.0;
  cder[n - 1] = 0.0;
  for (j = n - 2; j >= 0; j--)
    cder[j] = cder[j + 2] + 2 * (j + 1) * c[j + 1];
}
 
/* --------------------------------------------------------------------------*/
double
chebev (double a, double b, double c[], int m, double x)
    /* eq. 5.8.11 of C++ NR (2nd ed) */
{
  int j;
  double djp2, djp1, dj; /* d_{j+2}, d_{j+1} and d_j */
  double y;
 
  /* rescale input to lie within [-1,1] */
  y = 2*(x - 0.5*(b+a))/(b-a);
 
  dj = djp1 = 0;
  for(j = m-1 ; j >= 1; j--)
  { 
    /* advance the coefficients */
    djp2 = djp1; 
    djp1 = dj;
    dj   = 2*y*djp1 - djp2 + c[j];
  }
 
  return y*dj - djp1 + 0.5*c[0];
}
 
/* --------------------------------------------------------------------------*/
void
fourft (double *u, int N, int inv)
    /* a (slow) Fourier transform, seems to be just eq. 12.1.6 and 12.1.9 of C++ NR (2nd ed) */
{
  int l, k, iy, M;
  double x, x1, fac, Pi_fac, *a, *b;
 
  M = N / 2;
  a = dvector (0, M);
  b = dvector (1, M);       /* Actually: b=vector(1,M-1) but this is problematic if M=1*/
  fac = 1. / M;
  Pi_fac = Pi * fac;
  if (inv == 0)
  {
    for (l = 0; l <= M; l++)
    {
      a[l] = 0;
      if (l > 0 && l < M)
    b[l] = 0;
      x1 = Pi_fac * l;
      for (k = 0; k < N; k++)
      {
    x = x1 * k;
    a[l] += fac * u[k] * cos (x);
    if (l > 0 && l < M)
      b[l] += fac * u[k] * sin (x);
      }
    }
    u[0] = a[0];
    u[M] = a[M];
    for (l = 1; l < M; l++)
    {
      u[l] = a[l];
      u[l + M] = b[l];
    }
  }
  else
  {
    a[0] = u[0];
    a[M] = u[M];
    for (l = 1; l < M; l++)
    {
      a[l] = u[l];
      b[l] = u[M + l];
    }
    iy = 1;
    for (k = 0; k < N; k++)
    {
      u[k] = 0.5 * (a[0] + a[M] * iy);
      x1 = Pi_fac * k;
      for (l = 1; l < M; l++)
      {
    x = x1 * l;
    u[k] += a[l] * cos (x) + b[l] * sin (x);
      }
      iy = -iy;
    }
  }
  free_dvector (a, 0, M);
  free_dvector (b, 1, M);
}
 
/* -----------------------------------------*/
void
fourder (double u[], double du[], int N)
{
  int l, M, lpM;
 
  M = N / 2;
  du[0] = 0.;
  du[M] = 0.;
  for (l = 1; l < M; l++)
  {
    lpM = l + M;
    du[l] = u[lpM] * l;
    du[lpM] = -u[l] * l;
  }
}
 
/* -----------------------------------------*/
void
fourder2 (double u[], double d2u[], int N)
{
  int l, l2, M, lpM;
 
  d2u[0] = 0.;
  M = N / 2;
  for (l = 1; l <= M; l++)
  {
    l2 = l * l;
    lpM = l + M;
    d2u[l] = -u[l] * l2;
    if (l < M)
      d2u[lpM] = -u[lpM] * l2;
  }
}
 
/* ----------------------------------------- */
double
fourev (double *u, int N, double x)
{
  int l, M = N / 2;
  double xl, result;
 
  result = 0.5 * (u[0] + u[M] * cos (x * M));
  for (l = 1; l < M; l++)
  {
    xl = x * l;
    result += u[l] * cos (xl) + u[M + l] * sin (xl);
  }
  return result;
}
 
/* ------------------------------------------------------------------------*/
double
norm1 (double *v, int n)
{
  int i;
  double result = -1;
 
  for (i = 0; i < n; i++)
    if (fabs (v[i]) > result)
      result = fabs (v[i]);
 
  return result;
}
 
/* -------------------------------------------------------------------------*/
double
norm2 (double *v, int n)
{
  int i;
  double result = 0;
 
  for (i = 0; i < n; i++)
    result += v[i] * v[i];
 
  return sqrt (result);
}
 
/* -------------------------------------------------------------------------*/
double
scalarproduct (double *v, double *w, int n)
{
  int i;
  double result = 0;
 
  for (i = 0; i < n; i++)
    result += v[i] * w[i];
 
  return result;
}
 
/* -------------------------------------------------------------------------*/
 
} // namespac Utilities
} // namespace TP