13 |
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|
14 |
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static double m4tmp[4][4]; /* for efficiency */ |
15 |
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|
16 |
+ |
#ifdef BSD |
17 |
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#define copymat4(m4a,m4b) bcopy((char *)m4b,(char *)m4a,sizeof(m4tmp)) |
18 |
+ |
#else |
19 |
+ |
#define copymat4(m4a,m4b) (void)memcpy((char *)m4a,(char *)m4b,sizeof(m4tmp)) |
20 |
+ |
extern char *memcpy(); |
21 |
+ |
#endif |
22 |
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|
23 |
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24 |
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setident4(m4) |
56 |
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register double v3b[3]; |
57 |
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register double m4[4][4]; |
58 |
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{ |
59 |
< |
register int i; |
59 |
> |
m4tmp[0][0] = v3b[0]*m4[0][0] + v3b[1]*m4[1][0] + v3b[2]*m4[2][0]; |
60 |
> |
m4tmp[0][1] = v3b[0]*m4[0][1] + v3b[1]*m4[1][1] + v3b[2]*m4[2][1]; |
61 |
> |
m4tmp[0][2] = v3b[0]*m4[0][2] + v3b[1]*m4[1][2] + v3b[2]*m4[2][2]; |
62 |
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|
56 |
– |
for (i = 0; i < 3; i++) |
57 |
– |
m4tmp[0][i] = v3b[0]*m4[0][i] + |
58 |
– |
v3b[1]*m4[1][i] + |
59 |
– |
v3b[2]*m4[2][i]; |
60 |
– |
|
63 |
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v3a[0] = m4tmp[0][0]; |
64 |
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v3a[1] = m4tmp[0][1]; |
65 |
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v3a[2] = m4tmp[0][2]; |
81 |
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#ifdef INVMAT |
82 |
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/* |
83 |
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* invmat - computes the inverse of mat into inverse. Returns 1 |
84 |
< |
* if there exists an inverse, 0 otherwise. It uses Gause Elimination |
85 |
< |
* method. |
84 |
> |
* if there exists an inverse, 0 otherwise. It uses Gaussian Elimination |
85 |
> |
* method with partial pivoting. |
86 |
|
*/ |
87 |
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|
88 |
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invmat(inverse,mat) |
89 |
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double mat[4][4],inverse[4][4]; |
90 |
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{ |
91 |
|
#define SWAP(a,b,t) (t=a,a=b,b=t) |
92 |
+ |
#define ABS(x) (x>=0?x:-(x)) |
93 |
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|
94 |
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register int i,j,k; |
95 |
|
register double temp; |
96 |
|
|
94 |
– |
setident4(inverse); |
97 |
|
copymat4(m4tmp, mat); |
98 |
+ |
setident(inverse); |
99 |
|
|
100 |
|
for(i = 0; i < 4; i++) { |
101 |
< |
if(m4tmp[i][i] == 0) { /* Pivot is zero */ |
102 |
< |
/* Look for a raw with pivot != 0 and swap raws */ |
103 |
< |
for(j = i + 1; j < 4; j++) |
104 |
< |
if(m4tmp[j][i] != 0) { |
105 |
< |
for( k = 0; k < 4; k++) { |
106 |
< |
SWAP(m4tmp[i][k],m4tmp[j][k],temp); |
107 |
< |
SWAP(inverse[i][k],inverse[j][k],temp); |
108 |
< |
} |
109 |
< |
break; |
110 |
< |
} |
111 |
< |
if(j == 4) /* No replacing raw -> no inverse */ |
112 |
< |
return(0); |
113 |
< |
} |
101 |
> |
/* Look for row with largest pivot and swap rows */ |
102 |
> |
temp = 0; j = -1; |
103 |
> |
for(k = i; k < 4; k++) |
104 |
> |
if(ABS(m4tmp[k][i]) > temp) { |
105 |
> |
temp = ABS(m4tmp[k][i]); |
106 |
> |
j = k; |
107 |
> |
} |
108 |
> |
if(j == -1) /* No replacing row -> no inverse */ |
109 |
> |
return(0); |
110 |
> |
if (j != i) |
111 |
> |
for(k = 0; k < 4; k++) { |
112 |
> |
SWAP(m4tmp[i][k],m4tmp[j][k],temp); |
113 |
> |
SWAP(inverse[i][k],inverse[j][k],temp); |
114 |
> |
} |
115 |
|
|
116 |
|
temp = m4tmp[i][i]; |
117 |
|
for(k = 0; k < 4; k++) { |
129 |
|
} |
130 |
|
} |
131 |
|
return(1); |
132 |
+ |
|
133 |
+ |
#undef ABS |
134 |
+ |
#undef SWAP |
135 |
|
} |
136 |
|
#endif |