ultimatepp/bazaar/plugin/gdal/alg/thinplatespline.cpp
cxl 23ff1e7e82 .gdal moved to bazaar
git-svn-id: svn://ultimatepp.org/upp/trunk@9273 f0d560ea-af0d-0410-9eb7-867de7ffcac7
2015-12-07 13:36:24 +00:00

812 lines
24 KiB
C++

/******************************************************************************
* $Id: thinplatespline.cpp 27546 2014-07-22 22:40:02Z rouault $
*
* Project: GDAL Warp API
* Purpose: Implemenentation of 2D Thin Plate Spline transformer.
* Author: VIZRT Development Team.
*
* This code was provided by Gilad Ronnen (gro at visrt dot com) with
* permission to reuse under the following license.
*
******************************************************************************
* Copyright (c) 2004, VIZRT Inc.
* Copyright (c) 2008-2014, Even Rouault <even dot rouault at mines-paris dot org>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
****************************************************************************/
#ifdef HAVE_ARMADILLO
/* Include before #define A(r,c) because armadillo uses A in its include files */
#include "armadillo"
#endif
#include "thinplatespline.h"
/////////////////////////////////////////////////////////////////////////////////////
//// vizGeorefSpline2D
/////////////////////////////////////////////////////////////////////////////////////
#define A(r,c) _AA[ _nof_eqs * (r) + (c) ]
#define Ainv(r,c) _Ainv[ _nof_eqs * (r) + (c) ]
#define VIZ_GEOREF_SPLINE_DEBUG 0
#ifndef HAVE_ARMADILLO
static int matrixInvert( int N, double input[], double output[] );
#endif
void VizGeorefSpline2D::grow_points()
{
int new_max = _max_nof_points*2 + 2 + 3;
int i;
x = (double *) VSIRealloc( x, sizeof(double) * new_max );
y = (double *) VSIRealloc( y, sizeof(double) * new_max );
u = (double *) VSIRealloc( u, sizeof(double) * new_max );
unused = (int *) VSIRealloc( unused, sizeof(int) * new_max );
index = (int *) VSIRealloc( index, sizeof(int) * new_max );
for( i = 0; i < VIZGEOREF_MAX_VARS; i++ )
{
rhs[i] = (double *)
VSIRealloc( rhs[i], sizeof(double) * new_max );
coef[i] = (double *)
VSIRealloc( coef[i], sizeof(double) * new_max );
if( _max_nof_points == 0 )
{
memset(rhs[i], 0, 3 * sizeof(double));
memset(coef[i], 0, 3 * sizeof(double));
}
}
_max_nof_points = new_max - 3;
}
int VizGeorefSpline2D::add_point( const double Px, const double Py, const double *Pvars )
{
type = VIZ_GEOREF_SPLINE_POINT_WAS_ADDED;
int i;
if( _nof_points == _max_nof_points )
grow_points();
i = _nof_points;
//A new point is added
x[i] = Px;
y[i] = Py;
for ( int j = 0; j < _nof_vars; j++ )
rhs[j][i+3] = Pvars[j];
_nof_points++;
return 1;
}
#if 0
bool VizGeorefSpline2D::change_point(int index, double Px, double Py, double* Pvars)
{
if ( index < _nof_points )
{
int i = index;
x[i] = Px;
y[i] = Py;
for ( int j = 0; j < _nof_vars; j++ )
rhs[j][i+3] = Pvars[j];
}
return( true );
}
bool VizGeorefSpline2D::get_xy(int index, double& outX, double& outY)
{
bool ok;
if ( index < _nof_points )
{
ok = true;
outX = x[index];
outY = y[index];
}
else
{
ok = false;
outX = outY = 0.0f;
}
return(ok);
}
int VizGeorefSpline2D::delete_point(const double Px, const double Py )
{
for ( int i = 0; i < _nof_points; i++ )
{
if ( ( fabs(Px - x[i]) <= _tx ) && ( fabs(Py - y[i]) <= _ty ) )
{
for ( int j = i; j < _nof_points - 1; j++ )
{
x[j] = x[j+1];
y[j] = y[j+1];
for ( int k = 0; k < _nof_vars; k++ )
rhs[k][j+3] = rhs[k][j+3+1];
}
_nof_points--;
type = VIZ_GEOREF_SPLINE_POINT_WAS_DELETED;
return(1);
}
}
return(0);
}
#endif
#define SQ(x) ((x)*(x))
static CPL_INLINE double VizGeorefSpline2DBase_func( const double x1, const double y1,
const double x2, const double y2 )
{
double dist = SQ( x2 - x1 ) + SQ( y2 - y1 );
return dist ? dist * log( dist ) : 0.0;
}
#if defined(__GNUC__) && defined(__x86_64__)
/* Derived and adapted from code originating from: */
/* @(#)e_log.c 1.3 95/01/18 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunSoft, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/* __ieee754_log(x)
* Return the logrithm of x
*
* Method :
* 1. Argument Reduction: find k and f such that
* x = 2^k * (1+f),
* where sqrt(2)/2 < 1+f < sqrt(2) .
*
* 2. Approximation of log(1+f).
* Let s = f/(2+f) ; based on log(1+f) = log(1+s) - log(1-s)
* = 2s + 2/3 s**3 + 2/5 s**5 + .....,
* = 2s + s*R
* We use a special Reme algorithm on [0,0.1716] to generate
* a polynomial of degree 14 to approximate R The maximum error
* of this polynomial approximation is bounded by 2**-58.45. In
* other words,
* 2 4 6 8 10 12 14
* R(z) ~ Lg1*s +Lg2*s +Lg3*s +Lg4*s +Lg5*s +Lg6*s +Lg7*s
* (the values of Lg1 to Lg7 are listed in the program)
* and
* | 2 14 | -58.45
* | Lg1*s +...+Lg7*s - R(z) | <= 2
* | |
* Note that 2s = f - s*f = f - hfsq + s*hfsq, where hfsq = f*f/2.
* In order to guarantee error in log below 1ulp, we compute log
* by
* log(1+f) = f - s*(f - R) (if f is not too large)
* log(1+f) = f - (hfsq - s*(hfsq+R)). (better accuracy)
*
* 3. Finally, log(x) = k*ln2 + log(1+f).
* = k*ln2_hi+(f-(hfsq-(s*(hfsq+R)+k*ln2_lo)))
* Here ln2 is split into two floating point number:
* ln2_hi + ln2_lo,
* where n*ln2_hi is always exact for |n| < 2000.
*
* Special cases:
* log(x) is NaN with signal if x < 0 (including -INF) ;
* log(+INF) is +INF; log(0) is -INF with signal;
* log(NaN) is that NaN with no signal.
*
* Accuracy:
* according to an error analysis, the error is always less than
* 1 ulp (unit in the last place).
*
* Constants:
* The hexadecimal values are the intended ones for the following
* constants. The decimal values may be used, provided that the
* compiler will convert from decimal to binary accurately enough
* to produce the hexadecimal values shown.
*/
typedef double V2DF __attribute__ ((__vector_size__ (16)));
typedef union
{
V2DF v2;
double d[2];
} v2dfunion;
typedef union
{
int i[2];
long long li;
} i64union;
static const V2DF
v2_ln2_div_2pow20 = {6.93147180559945286e-01 / 1048576, 6.93147180559945286e-01 / 1048576},
v2_Lg1 = {6.666666666666735130e-01, 6.666666666666735130e-01},
v2_Lg2 = {3.999999999940941908e-01, 3.999999999940941908e-01},
v2_Lg3 = {2.857142874366239149e-01, 2.857142874366239149e-01},
v2_Lg4 = {2.222219843214978396e-01, 2.222219843214978396e-01},
v2_Lg5 = {1.818357216161805012e-01, 1.818357216161805012e-01},
v2_Lg6 = {1.531383769920937332e-01, 1.531383769920937332e-01},
/*v2_Lg7 = {1.479819860511658591e-01, 1.479819860511658591e-01}, */
v2_one = { 1.0, 1.0 },
v2_const1023_mul_2pow20 = { 1023.0 * 1048576, 1023.0 * 1048576};
#define GET_HIGH_WORD(hx,x) memcpy(&hx,((char*)&x+4),4)
#define SET_HIGH_WORD(x,hx) memcpy(((char*)&x+4),&hx,4)
#define MAKE_WIDE_CST(x) ((((long long)(x)) << 32) | (x))
static const long long cst_expmask = MAKE_WIDE_CST(0xfff00000);
static const long long cst_0x95f64 = MAKE_WIDE_CST(0x00095f64);
static const long long cst_0x100000 = MAKE_WIDE_CST(0x00100000);
static const long long cst_0x3ff00000 = MAKE_WIDE_CST(0x3ff00000);
/* Modified version of __ieee754_log(), less precise than log() but a bit */
/* faste, and computing 4 log() at a time. Assumes that the values are > 0 */
static void FastApproxLog4Val(v2dfunion* x)
{
V2DF f[2],s[2],z[2],R[2],w[2],t1[2],t2[2];
v2dfunion dk[2];
i64union k[2], hx[2], i[2];
GET_HIGH_WORD(hx[0].i[0],x[0].d[0]);
GET_HIGH_WORD(hx[0].i[1],x[0].d[1]);
k[0].li = hx[0].li & cst_expmask;
hx[0].li &= ~cst_expmask;
i[0].li = (hx[0].li + cst_0x95f64) & cst_0x100000;
hx[0].li |= i[0].li ^ cst_0x3ff00000;
SET_HIGH_WORD(x[0].d[0],hx[0].i[0]); /* normalize x or x/2 */
SET_HIGH_WORD(x[0].d[1],hx[0].i[1]); /* normalize x or x/2 */
k[0].li += i[0].li;
dk[0].d[0] = (double)k[0].i[0];
dk[0].d[1] = (double)k[0].i[1];
GET_HIGH_WORD(hx[1].i[0],x[1].d[0]);
GET_HIGH_WORD(hx[1].i[1],x[1].d[1]);
k[1].li = hx[1].li & cst_expmask;
hx[1].li &= ~cst_expmask;
i[1].li = (hx[1].li + cst_0x95f64) & cst_0x100000;
hx[1].li |= i[1].li ^ cst_0x3ff00000;
SET_HIGH_WORD(x[1].d[0],hx[1].i[0]); /* normalize x or x/2 */
SET_HIGH_WORD(x[1].d[1],hx[1].i[1]); /* normalize x or x/2 */
k[1].li += i[1].li;
dk[1].d[0] = (double)k[1].i[0];
dk[1].d[1] = (double)k[1].i[1];
f[0] = x[0].v2-v2_one;
s[0] = f[0]/(x[0].v2+v2_one);
z[0] = s[0]*s[0];
w[0] = z[0]*z[0];
t1[0]= w[0]*(v2_Lg2+w[0]*(v2_Lg4+w[0]*v2_Lg6));
t2[0]= z[0]*(v2_Lg1+w[0]*(v2_Lg3+w[0]*(v2_Lg5/*+w[0]*v2_Lg7*/)));
R[0] = t2[0]+t1[0];
x[0].v2 = ((dk[0].v2 - v2_const1023_mul_2pow20)*v2_ln2_div_2pow20-(s[0]*(f[0]-R[0])-f[0]));
f[1] = x[1].v2-v2_one;
s[1] = f[1]/(x[1].v2+v2_one);
z[1] = s[1]*s[1];
w[1] = z[1]*z[1];
t1[1]= w[1]*(v2_Lg2+w[1]*(v2_Lg4+w[1]*v2_Lg6));
t2[1]= z[1]*(v2_Lg1+w[1]*(v2_Lg3+w[1]*(v2_Lg5/*+w[1]*v2_Lg7*/)));
R[1] = t2[1]+t1[1];
x[1].v2 = ((dk[1].v2- v2_const1023_mul_2pow20)*v2_ln2_div_2pow20-(s[1]*(f[1]-R[1])-f[1]));
}
static CPL_INLINE void VizGeorefSpline2DBase_func4( double* res,
const double* pxy,
const double* xr, const double* yr )
{
v2dfunion x1v, y1v, xv[2], yv[2], dist[2], resv[2];
xv[0].d[0] = xr[0];
xv[0].d[1] = xr[1];
xv[1].d[0] = xr[2];
xv[1].d[1] = xr[3];
yv[0].d[0] = yr[0];
yv[0].d[1] = yr[1];
yv[1].d[0] = yr[2];
yv[1].d[1] = yr[3];
x1v.d[0] = pxy[0];
x1v.d[1] = pxy[0];
y1v.d[0] = pxy[1];
y1v.d[1] = pxy[1];
dist[0].v2 = SQ( xv[0].v2 - x1v.v2 ) + SQ( yv[0].v2 - y1v.v2 );
dist[1].v2 = SQ( xv[1].v2 - x1v.v2 ) + SQ( yv[1].v2 - y1v.v2 );
resv[0] = dist[0];
resv[1] = dist[1];
FastApproxLog4Val(dist);
resv[0].v2 *= dist[0].v2;
resv[1].v2 *= dist[1].v2;
res[0] = resv[0].d[0];
res[1] = resv[0].d[1];
res[2] = resv[1].d[0];
res[3] = resv[1].d[1];
}
#else
static void VizGeorefSpline2DBase_func4( double* res,
const double* pxy,
const double* xr, const double* yr )
{
double dist0 = SQ( xr[0] - pxy[0] ) + SQ( yr[0] - pxy[1] );
res[0] = dist0 ? dist0 * log(dist0) : 0.0;
double dist1 = SQ( xr[1] - pxy[0] ) + SQ( yr[1] - pxy[1] );
res[1] = dist1 ? dist1 * log(dist1) : 0.0;
double dist2 = SQ( xr[2] - pxy[0] ) + SQ( yr[2] - pxy[1] );
res[2] = dist2 ? dist2 * log(dist2) : 0.0;
double dist3 = SQ( xr[3] - pxy[0] ) + SQ( yr[3] - pxy[1] );
res[3] = dist3 ? dist3 * log(dist3) : 0.0;
}
#endif
int VizGeorefSpline2D::solve(void)
{
int r, c;
int p;
// No points at all
if ( _nof_points < 1 )
{
type = VIZ_GEOREF_SPLINE_ZERO_POINTS;
return(0);
}
// Only one point
if ( _nof_points == 1 )
{
type = VIZ_GEOREF_SPLINE_ONE_POINT;
return(1);
}
// Just 2 points - it is necessarily 1D case
if ( _nof_points == 2 )
{
_dx = x[1] - x[0];
_dy = y[1] - y[0];
double fact = 1.0 / ( _dx * _dx + _dy * _dy );
_dx *= fact;
_dy *= fact;
type = VIZ_GEOREF_SPLINE_TWO_POINTS;
return(2);
}
// More than 2 points - first we have to check if it is 1D or 2D case
double xmax = x[0], xmin = x[0], ymax = y[0], ymin = y[0];
double delx, dely;
double xx, yy;
double sumx = 0.0f, sumy= 0.0f, sumx2 = 0.0f, sumy2 = 0.0f, sumxy = 0.0f;
double SSxx, SSyy, SSxy;
for ( p = 0; p < _nof_points; p++ )
{
xx = x[p];
yy = y[p];
xmax = MAX( xmax, xx );
xmin = MIN( xmin, xx );
ymax = MAX( ymax, yy );
ymin = MIN( ymin, yy );
sumx += xx;
sumx2 += xx * xx;
sumy += yy;
sumy2 += yy * yy;
sumxy += xx * yy;
}
delx = xmax - xmin;
dely = ymax - ymin;
SSxx = sumx2 - sumx * sumx / _nof_points;
SSyy = sumy2 - sumy * sumy / _nof_points;
SSxy = sumxy - sumx * sumy / _nof_points;
if ( delx < 0.001 * dely || dely < 0.001 * delx ||
fabs ( SSxy * SSxy / ( SSxx * SSyy ) ) > 0.99 )
{
int p1;
type = VIZ_GEOREF_SPLINE_ONE_DIMENSIONAL;
_dx = _nof_points * sumx2 - sumx * sumx;
_dy = _nof_points * sumy2 - sumy * sumy;
double fact = 1.0 / sqrt( _dx * _dx + _dy * _dy );
_dx *= fact;
_dy *= fact;
for ( p = 0; p < _nof_points; p++ )
{
double dxp = x[p] - x[0];
double dyp = y[p] - y[0];
u[p] = _dx * dxp + _dy * dyp;
unused[p] = 1;
}
for ( p = 0; p < _nof_points; p++ )
{
int min_index = -1;
double min_u = 0;
for ( p1 = 0; p1 < _nof_points; p1++ )
{
if ( unused[p1] )
{
if ( min_index < 0 || u[p1] < min_u )
{
min_index = p1;
min_u = u[p1];
}
}
}
index[p] = min_index;
unused[min_index] = 0;
}
return(3);
}
type = VIZ_GEOREF_SPLINE_FULL;
// Make the necessary memory allocations
_nof_eqs = _nof_points + 3;
if( _nof_eqs > INT_MAX / _nof_eqs )
{
CPLError(CE_Failure, CPLE_AppDefined, "Too many coefficients. Computation aborted.");
return 0;
}
double* _AA = ( double * )VSICalloc( _nof_eqs * _nof_eqs, sizeof( double ) );
double* _Ainv = ( double * )VSICalloc( _nof_eqs * _nof_eqs, sizeof( double ) );
if( _AA == NULL || _Ainv == NULL )
{
CPLError(CE_Failure, CPLE_AppDefined, "Out-of-memory while allocating temporary arrays. Computation aborted.");
VSIFree(_AA);
VSIFree(_Ainv);
return 0;
}
// Calc the values of the matrix A
for ( r = 0; r < 3; r++ )
for ( c = 0; c < 3; c++ )
A(r,c) = 0.0;
for ( c = 0; c < _nof_points; c++ )
{
A(0,c+3) = 1.0;
A(1,c+3) = x[c];
A(2,c+3) = y[c];
A(c+3,0) = 1.0;
A(c+3,1) = x[c];
A(c+3,2) = y[c];
}
for ( r = 0; r < _nof_points; r++ )
for ( c = r; c < _nof_points; c++ )
{
A(r+3,c+3) = VizGeorefSpline2DBase_func( x[r], y[r], x[c], y[c] );
if ( r != c )
A(c+3,r+3 ) = A(r+3,c+3);
}
#if VIZ_GEOREF_SPLINE_DEBUG
for ( r = 0; r < _nof_eqs; r++ )
{
for ( c = 0; c < _nof_eqs; c++ )
fprintf(stderr, "%f", A(r,c));
fprintf(stderr, "\n");
}
#endif
int ret = 4;
#ifdef HAVE_ARMADILLO
try
{
arma::mat matA(_AA,_nof_eqs,_nof_eqs,false);
arma::mat matRHS(_nof_eqs, _nof_vars);
int row, col;
for(row = 0; row < _nof_eqs; row++)
for(col = 0; col < _nof_vars; col++)
matRHS.at(row, col) = rhs[col][row];
arma::mat matCoefs(_nof_vars, _nof_eqs);
if( !arma::solve(matCoefs, matA, matRHS) )
{
CPLError(CE_Failure, CPLE_AppDefined, "There is a problem to invert the interpolation matrix.");
ret = 0;
}
else
{
for(row = 0; row < _nof_eqs; row++)
for(col = 0; col < _nof_vars; col++)
coef[col][row] = matCoefs.at(row, col);
}
}
catch(...)
{
CPLError(CE_Failure, CPLE_AppDefined, "There is a problem to invert the interpolation matrix.");
ret = 0;
}
#else
// Invert the matrix
int status = matrixInvert( _nof_eqs, _AA, _Ainv );
if ( !status )
{
CPLError(CE_Failure, CPLE_AppDefined, "There is a problem to invert the interpolation matrix.");
ret = 0;
}
else
{
// calc the coefs
for ( int v = 0; v < _nof_vars; v++ )
for ( r = 0; r < _nof_eqs; r++ )
{
coef[v][r] = 0.0;
for ( c = 0; c < _nof_eqs; c++ )
coef[v][r] += Ainv(r,c) * rhs[v][c];
}
}
#endif
VSIFree(_AA);
VSIFree(_Ainv);
return(ret);
}
int VizGeorefSpline2D::get_point( const double Px, const double Py, double *vars )
{
int v, r;
double tmp, Pu;
double fact;
int leftP=0, rightP=0, found = 0;
switch ( type )
{
case VIZ_GEOREF_SPLINE_ZERO_POINTS :
for ( v = 0; v < _nof_vars; v++ )
vars[v] = 0.0;
break;
case VIZ_GEOREF_SPLINE_ONE_POINT :
for ( v = 0; v < _nof_vars; v++ )
vars[v] = rhs[v][3];
break;
case VIZ_GEOREF_SPLINE_TWO_POINTS :
fact = _dx * ( Px - x[0] ) + _dy * ( Py - y[0] );
for ( v = 0; v < _nof_vars; v++ )
vars[v] = ( 1 - fact ) * rhs[v][3] + fact * rhs[v][4];
break;
case VIZ_GEOREF_SPLINE_ONE_DIMENSIONAL :
Pu = _dx * ( Px - x[0] ) + _dy * ( Py - y[0] );
if ( Pu <= u[index[0]] )
{
leftP = index[0];
rightP = index[1];
}
else if ( Pu >= u[index[_nof_points-1]] )
{
leftP = index[_nof_points-2];
rightP = index[_nof_points-1];
}
else
{
for ( r = 1; !found && r < _nof_points; r++ )
{
leftP = index[r-1];
rightP = index[r];
if ( Pu >= u[leftP] && Pu <= u[rightP] )
found = 1;
}
}
fact = ( Pu - u[leftP] ) / ( u[rightP] - u[leftP] );
for ( v = 0; v < _nof_vars; v++ )
vars[v] = ( 1.0 - fact ) * rhs[v][leftP+3] +
fact * rhs[v][rightP+3];
break;
case VIZ_GEOREF_SPLINE_FULL :
{
double Pxy[2] = { Px, Py };
for ( v = 0; v < _nof_vars; v++ )
vars[v] = coef[v][0] + coef[v][1] * Px + coef[v][2] * Py;
for ( r = 0; r < (_nof_points & (~3)); r+=4 )
{
double tmp[4];
VizGeorefSpline2DBase_func4( tmp, Pxy, &x[r], &y[r] );
for ( v= 0; v < _nof_vars; v++ )
vars[v] += coef[v][r+3] * tmp[0] +
coef[v][r+3+1] * tmp[1] +
coef[v][r+3+2] * tmp[2] +
coef[v][r+3+3] * tmp[3];
}
for ( ; r < _nof_points; r++ )
{
tmp = VizGeorefSpline2DBase_func( Px, Py, x[r], y[r] );
for ( v= 0; v < _nof_vars; v++ )
vars[v] += coef[v][r+3] * tmp;
}
break;
}
case VIZ_GEOREF_SPLINE_POINT_WAS_ADDED :
fprintf(stderr, " A point was added after the last solve\n");
fprintf(stderr, " NO interpolation - return values are zero\n");
for ( v = 0; v < _nof_vars; v++ )
vars[v] = 0.0;
return(0);
break;
case VIZ_GEOREF_SPLINE_POINT_WAS_DELETED :
fprintf(stderr, " A point was deleted after the last solve\n");
fprintf(stderr, " NO interpolation - return values are zero\n");
for ( v = 0; v < _nof_vars; v++ )
vars[v] = 0.0;
return(0);
break;
default :
return(0);
break;
}
return(1);
}
#ifndef HAVE_ARMADILLO
static int matrixInvert( int N, double input[], double output[] )
{
// Receives an array of dimension NxN as input. This is passed as a one-
// dimensional array of N-squared size. It produces the inverse of the
// input matrix, returned as output, also of size N-squared. The Gauss-
// Jordan Elimination method is used. (Adapted from a BASIC routine in
// "Basic Scientific Subroutines Vol. 1", courtesy of Scott Edwards.)
// Array elements 0...N-1 are for the first row, N...2N-1 are for the
// second row, etc.
// We need to have a temporary array of size N x 2N. We'll refer to the
// "left" and "right" halves of this array.
int row, col;
#if 0
fprintf(stderr, "Matrix Inversion input matrix (N=%d)\n", N);
for ( row=0; row<N; row++ )
{
for ( col=0; col<N; col++ )
{
fprintf(stderr, "%5.2f ", input[row*N + col ] );
}
fprintf(stderr, "\n");
}
#endif
int tempSize = 2 * N * N;
double* temp = (double*) new double[ tempSize ];
double ftemp;
if (temp == 0) {
CPLError(CE_Failure, CPLE_AppDefined, "matrixInvert(): ERROR - memory allocation failed.");
return false;
}
// First create a double-width matrix with the input array on the left
// and the identity matrix on the right.
for ( row=0; row<N; row++ )
{
for ( col=0; col<N; col++ )
{
// Our index into the temp array is X2 because it's twice as wide
// as the input matrix.
temp[ 2*row*N + col ] = input[ row*N+col ]; // left = input matrix
temp[ 2*row*N + col + N ] = 0.0f; // right = 0
}
temp[ 2*row*N + row + N ] = 1.0f; // 1 on the diagonal of RHS
}
// Now perform row-oriented operations to convert the left hand side
// of temp to the identity matrix. The inverse of input will then be
// on the right.
int max;
int k=0;
for (k = 0; k < N; k++)
{
if (k+1 < N) // if not on the last row
{
max = k;
for (row = k+1; row < N; row++) // find the maximum element
{
if (fabs( temp[row*2*N + k] ) > fabs( temp[max*2*N + k] ))
{
max = row;
}
}
if (max != k) // swap all the elements in the two rows
{
for (col=k; col<2*N; col++)
{
ftemp = temp[k*2*N + col];
temp[k*2*N + col] = temp[max*2*N + col];
temp[max*2*N + col] = ftemp;
}
}
}
ftemp = temp[ k*2*N + k ];
if ( ftemp == 0.0f ) // matrix cannot be inverted
{
delete[] temp;
return false;
}
for ( col=k; col<2*N; col++ )
{
temp[ k*2*N + col ] /= ftemp;
}
int i2 = k*2*N ;
for ( row=0; row<N; row++ )
{
if ( row != k )
{
int i1 = row*2*N;
ftemp = temp[ i1 + k ];
for ( col=k; col<2*N; col++ )
{
temp[ i1 + col ] -= ftemp * temp[ i2 + col ];
}
}
}
}
// Retrieve inverse from the right side of temp
for (row = 0; row < N; row++)
{
for (col = 0; col < N; col++)
{
output[row*N + col] = temp[row*2*N + col + N ];
}
}
#if 0
fprintf(stderr, "Matrix Inversion result matrix:\n");
for ( row=0; row<N; row++ )
{
for ( col=0; col<N; col++ )
{
fprintf(stderr, "%5.2f ", output[row*N + col ] );
}
fprintf(stderr, "\n");
}
#endif
delete [] temp; // free memory
return true;
}
#endif