| 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" |
| # | User | Rev | Content |
|---|---|---|---|
| 1 | greg | 2.1 | #ifndef lint |
| 2 | greg | 2.2 | static const char RCSid[] = "$Id$"; |
| 3 | greg | 2.1 | #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 | greg | 2.3 | #include "copyright.h" |
| 11 | greg | 2.2 | |
| 12 | greg | 2.1 | #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 | greg | 2.2 | int |
| 21 | invmat4(inverse, mat) | ||
| 22 | greg | 2.1 | 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 | greg | 2.2 | setident4(inverse); |
| 31 | greg | 2.1 | |
| 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 | } |