src/common/invmat4.c

#ifndef lint
static const char       RCSid[] = "$Id$";
#endif
/*
 * invmat4 - computes the inverse of mat into inverse.  Returns 1
 * if there exists an inverse, 0 otherwise.  It uses Gaussian Elimination
 * method.
 */

/* ====================================================================
 * The Radiance Software License, Version 1.0
 *
 * Copyright (c) 1990 - 2002 The Regents of the University of California,
 * through Lawrence Berkeley National Laboratory.   All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *         notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *           if any, must include the following acknowledgment:
 *             "This product includes Radiance software
 *                 (http://radsite.lbl.gov/)
 *                 developed by the Lawrence Berkeley National Laboratory
 *               (http://www.lbl.gov/)."
 *       Alternately, this acknowledgment may appear in the software itself,
 *       if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
 *       and "The Regents of the University of California" must
 *       not be used to endorse or promote products derived from this
 *       software without prior written permission. For written
 *       permission, please contact [email protected].
 *
 * 5. Products derived from this software may not be called "Radiance",
 *       nor may "Radiance" appear in their name, without prior written
 *       permission of Lawrence Berkeley National Laboratory.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.   IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Lawrence Berkeley National Laboratory.   For more
 * information on Lawrence Berkeley National Laboratory, please see
 * <http://www.lbl.gov/>.
 */

#include "mat4.h"


#define  ABS(x)         ((x)>=0 ? (x) : -(x))

#define SWAP(a,b,t) (t=a,a=b,b=t)


int
invmat4(inverse, mat)
MAT4  inverse, mat;
{
        MAT4  m4tmp;
        register int i,j,k;
        register double temp;

        copymat4(m4tmp, mat);
                                        /* set inverse to identity */
        setident4(inverse);

        for(i = 0; i < 4; i++) {
                /* Look for row with largest pivot and swap rows */
                temp = FTINY; j = -1;
                for(k = i; k < 4; k++)
                        if(ABS(m4tmp[k][i]) > temp) {
                                temp = ABS(m4tmp[k][i]);
                                j = k;
                                }
                if(j == -1)     /* No replacing row -> no inverse */
                        return(0);
                if (j != i)
                        for(k = 0; k < 4; k++) {
                                SWAP(m4tmp[i][k],m4tmp[j][k],temp);
                                SWAP(inverse[i][k],inverse[j][k],temp);
                                }

                temp = m4tmp[i][i];
                for(k = 0; k < 4; k++) {
                        m4tmp[i][k] /= temp;
                        inverse[i][k] /= temp;
                        }
                for(j = 0; j < 4; j++) {
                        if(j != i) {
                                temp = m4tmp[j][i];
                                for(k = 0; k < 4; k++) {
                                        m4tmp[j][k] -= m4tmp[i][k]*temp;
                                        inverse[j][k] -= inverse[i][k]*temp;
                                        }
                                }
                        }
                }
        return(1);
}
Revision:	2.2
Committed:	Sat Feb 22 02:07:22 2003 UTC (21 years, 2 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.1:	+61 -8 lines
Log Message:	Changes and check-in for 3.5 release Includes new source files and modifications not recorded for many years See ray/doc/notes/ReleaseNotes for notes between 3.1 and 3.5 release
#	Content
1	#ifndef lint
2	static const char RCSid[] = "$Id$";
3	#endif
4	/*
5	* invmat4 - computes the inverse of mat into inverse. Returns 1
6	* if there exists an inverse, 0 otherwise. It uses Gaussian Elimination
7	* method.
8	*/
9
10	/* ====================================================================
11	* The Radiance Software License, Version 1.0
12	*
13	* Copyright (c) 1990 - 2002 The Regents of the University of California,
14	* through Lawrence Berkeley National Laboratory. All rights reserved.
15	*
16	* Redistribution and use in source and binary forms, with or without
17	* modification, are permitted provided that the following conditions
18	* are met:
19	*
20	* 1. Redistributions of source code must retain the above copyright
21	* notice, this list of conditions and the following disclaimer.
22	*
23	* 2. Redistributions in binary form must reproduce the above copyright
24	* notice, this list of conditions and the following disclaimer in
25	* the documentation and/or other materials provided with the
26	* distribution.
27	*
28	* 3. The end-user documentation included with the redistribution,
29	* if any, must include the following acknowledgment:
30	* "This product includes Radiance software
31	* (http://radsite.lbl.gov/)
32	* developed by the Lawrence Berkeley National Laboratory
33	* (http://www.lbl.gov/)."
34	* Alternately, this acknowledgment may appear in the software itself,
35	* if and wherever such third-party acknowledgments normally appear.
36	*
37	* 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
38	* and "The Regents of the University of California" must
39	* not be used to endorse or promote products derived from this
40	* software without prior written permission. For written
41	* permission, please contact [email protected].
42	*
43	* 5. Products derived from this software may not be called "Radiance",
44	* nor may "Radiance" appear in their name, without prior written
45	* permission of Lawrence Berkeley National Laboratory.
46	*
47	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
48	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
49	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
50	* DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
51	* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
52	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
53	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
54	* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
55	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
56	* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
57	* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
58	* SUCH DAMAGE.
59	* ====================================================================
60	*
61	* This software consists of voluntary contributions made by many
62	* individuals on behalf of Lawrence Berkeley National Laboratory. For more
63	* information on Lawrence Berkeley National Laboratory, please see
64	* <http://www.lbl.gov/>.
65	*/
66
67	#include "mat4.h"
68
69
70	#define ABS(x) ((x)>=0 ? (x) : -(x))
71
72	#define SWAP(a,b,t) (t=a,a=b,b=t)
73
74
75	int
76	invmat4(inverse, mat)
77	MAT4 inverse, mat;
78	{
79	MAT4 m4tmp;
80	register int i,j,k;
81	register double temp;
82
83	copymat4(m4tmp, mat);
84	/* set inverse to identity */
85	setident4(inverse);
86
87	for(i = 0; i < 4; i++) {
88	/* Look for row with largest pivot and swap rows */
89	temp = FTINY; j = -1;
90	for(k = i; k < 4; k++)
91	if(ABS(m4tmp[k][i]) > temp) {
92	temp = ABS(m4tmp[k][i]);
93	j = k;
94	}
95	if(j == -1) /* No replacing row -> no inverse */
96	return(0);
97	if (j != i)
98	for(k = 0; k < 4; k++) {
99	SWAP(m4tmp[i][k],m4tmp[j][k],temp);
100	SWAP(inverse[i][k],inverse[j][k],temp);
101	}
102
103	temp = m4tmp[i][i];
104	for(k = 0; k < 4; k++) {
105	m4tmp[i][k] /= temp;
106	inverse[i][k] /= temp;
107	}
108	for(j = 0; j < 4; j++) {
109	if(j != i) {
110	temp = m4tmp[j][i];
111	for(k = 0; k < 4; k++) {
112	m4tmp[j][k] -= m4tmp[i][k]*temp;
113	inverse[j][k] -= inverse[i][k]*temp;
114	}
115	}
116	}
117	}
118	return(1);
119	}