| Revision: | 2.3 |
| Committed: | Tue Feb 25 02:47:21 2003 UTC (22 years, 2 months ago) by greg |
| Content type: | text/plain |
| Branch: | MAIN |
| CVS Tags: | rad5R4, rad5R2, rad4R2P2, rad5R0, rad5R1, rad3R7P2, rad3R7P1, rad4R2, rad4R1, rad4R0, rad3R5, rad3R6, rad3R6P1, rad3R8, rad3R9, rad4R2P1, rad5R3, HEAD |
| Changes since 2.2: | +1 -56 lines |
| Log Message: | Replaced inline copyright notice with #include "copyright.h" |
| # | 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 | #include "copyright.h" |
| 11 | |
| 12 | #include "mat4.h" |
| 13 | |
| 14 | |
| 15 | #define ABS(x) ((x)>=0 ? (x) : -(x)) |
| 16 | |
| 17 | #define SWAP(a,b,t) (t=a,a=b,b=t) |
| 18 | |
| 19 | |
| 20 | int |
| 21 | invmat4(inverse, mat) |
| 22 | MAT4 inverse, mat; |
| 23 | { |
| 24 | MAT4 m4tmp; |
| 25 | register int i,j,k; |
| 26 | register double temp; |
| 27 | |
| 28 | copymat4(m4tmp, mat); |
| 29 | /* set inverse to identity */ |
| 30 | setident4(inverse); |
| 31 | |
| 32 | for(i = 0; i < 4; i++) { |
| 33 | /* Look for row with largest pivot and swap rows */ |
| 34 | temp = FTINY; j = -1; |
| 35 | for(k = i; k < 4; k++) |
| 36 | if(ABS(m4tmp[k][i]) > temp) { |
| 37 | temp = ABS(m4tmp[k][i]); |
| 38 | j = k; |
| 39 | } |
| 40 | if(j == -1) /* No replacing row -> no inverse */ |
| 41 | return(0); |
| 42 | if (j != i) |
| 43 | for(k = 0; k < 4; k++) { |
| 44 | SWAP(m4tmp[i][k],m4tmp[j][k],temp); |
| 45 | SWAP(inverse[i][k],inverse[j][k],temp); |
| 46 | } |
| 47 | |
| 48 | temp = m4tmp[i][i]; |
| 49 | for(k = 0; k < 4; k++) { |
| 50 | m4tmp[i][k] /= temp; |
| 51 | inverse[i][k] /= temp; |
| 52 | } |
| 53 | for(j = 0; j < 4; j++) { |
| 54 | if(j != i) { |
| 55 | temp = m4tmp[j][i]; |
| 56 | for(k = 0; k < 4; k++) { |
| 57 | m4tmp[j][k] -= m4tmp[i][k]*temp; |
| 58 | inverse[j][k] -= inverse[i][k]*temp; |
| 59 | } |
| 60 | } |
| 61 | } |
| 62 | } |
| 63 | return(1); |
| 64 | } |