1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134
|
/*
* Copyright (C) 1998, 2000-2007, 2010, 2011, 2012, 2013 SINTEF ICT,
* Applied Mathematics, Norway.
*
* Contact information: E-mail: tor.dokken@sintef.no
* SINTEF ICT, Department of Applied Mathematics,
* P.O. Box 124 Blindern,
* 0314 Oslo, Norway.
*
* This file is part of SISL.
*
* SISL is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* SISL is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public
* License along with SISL. If not, see
* <http://www.gnu.org/licenses/>.
*
* In accordance with Section 7(b) of the GNU Affero General Public
* License, a covered work must retain the producer line in every data
* file that is created or manipulated using SISL.
*
* Other Usage
* You can be released from the requirements of the license by purchasing
* a commercial license. Buying such a license is mandatory as soon as you
* develop commercial activities involving the SISL library without
* disclosing the source code of your own applications.
*
* This file may be used in accordance with the terms contained in a
* written agreement between you and SINTEF ICT.
*/
#include "sisl-copyright.h"
/*
*
* $Id: s6crvature.c,v 1.1 1994-04-21 12:10:42 boh Exp $
*
*/
#define S6CURVATURE
#include "sislP.h"
#if defined(SISLNEEDPROTOTYPES)
void
s6curvature(double eder[],int idim,double ecurv[],int *jstat)
#else
void s6curvature(eder,idim,ecurv,jstat)
int idim,*jstat;
double eder[],ecurv[];
#endif
/*
*********************************************************************
*
* PURPOSE : Given position, first and second derivative of a curve at
* a point, compute curvature vector.
*
*
*
* INPUT : eder - Array containing position, 1. and 2. derivative of
* curve. Dimension is 3*idim.
* idim - Dimension of geometry space.
*
*
* OUTPUT : ecurv - Curvature vector.
* jstat - status messages
* = 1 : Tangent vector zero.
* = 0 : ok
* < 0 : error
*
*
* METHOD : Express the curve using cord length parametrisation. Then the
* curvature is equal to the 2. derivative of the curve.
*
* REFERENCES :
*
* USE :
*
*-
* CALLS : s6length - Length of vector.
* s6scpr - Scalar product between two vectors.
*
* WRITTEN BY : Vibeke Skytt, SI, 04.90.
*
*********************************************************************
*/
{
int kstat = 0; /* Status variable. */
int ki; /* Counter. */
double tleng; /* Length of first derivative. */
double tleng2; /* Square of length. */
double tdot; /* Scalar product between 1. and 2. derivative. */
/* Compute length of 1. derivative. */
tleng = s6length(eder+idim,idim,&kstat);
if (kstat == 0)
{
/* The first derivative is zero. */
for (ki=0; ki<idim; ki++) ecurv[ki] = (double)0.0;
goto warn1;
}
else
{
tleng2 = tleng*tleng;
tdot = s6scpr(eder+idim,eder+2*idim,idim);
for (ki=0; ki<idim; ki++)
ecurv[ki] = (eder[2*idim+ki] - eder[idim*ki]*tdot/tleng2)/tleng2;
}
*jstat = 0;
goto out;
warn1 :
*jstat = 1;
goto out;
out :
return;
}
|