| Revision: | 2.5 |
| Committed: | Thu Jul 17 09:21:29 2003 UTC (21 years, 9 months ago) by schorsch |
| Content type: | text/plain |
| Branch: | MAIN |
| CVS Tags: | rad5R4, rad5R2, rad4R2P2, rad5R0, rad5R1, rad3R7P2, rad3R7P1, rad4R2, rad4R1, rad4R0, rad3R6, rad3R6P1, rad3R8, rad3R9, rad4R2P1, rad5R3, HEAD |
| Changes since 2.4: | +2 -2 lines |
| Log Message: | Added prototypes and includes from patch by Randolph Fritz. Added more required includes and reduced other compile warnings. |
| # | Content |
|---|---|
| 1 | #ifndef lint |
| 2 | static const char RCSid[] = "$Id: zeroes.c,v 2.4 2003/02/25 02:47:22 greg Exp $"; |
| 3 | #endif |
| 4 | /* |
| 5 | * zeroes.c - compute roots for various equations. |
| 6 | * |
| 7 | * External symbols declared in standard.h |
| 8 | */ |
| 9 | |
| 10 | #include "copyright.h" |
| 11 | |
| 12 | |
| 13 | #include <math.h> |
| 14 | |
| 15 | #include "fvect.h" |
| 16 | #include "rtmath.h" |
| 17 | |
| 18 | int |
| 19 | quadratic(r, a, b, c) /* find real roots of quadratic equation */ |
| 20 | double *r; /* roots in ascending order */ |
| 21 | double a, b, c; |
| 22 | { |
| 23 | double disc; |
| 24 | int first; |
| 25 | |
| 26 | if (a < -FTINY) |
| 27 | first = 1; |
| 28 | else if (a > FTINY) |
| 29 | first = 0; |
| 30 | else if (fabs(b) > FTINY) { /* solve linearly */ |
| 31 | r[0] = -c/b; |
| 32 | return(1); |
| 33 | } else |
| 34 | return(0); /* equation is c == 0 ! */ |
| 35 | |
| 36 | b *= 0.5; /* simplifies formula */ |
| 37 | |
| 38 | disc = b*b - a*c; /* discriminant */ |
| 39 | |
| 40 | if (disc < -FTINY*FTINY) /* no real roots */ |
| 41 | return(0); |
| 42 | |
| 43 | if (disc <= FTINY*FTINY) { /* double root */ |
| 44 | r[0] = -b/a; |
| 45 | return(1); |
| 46 | } |
| 47 | |
| 48 | disc = sqrt(disc); |
| 49 | |
| 50 | r[first] = (-b - disc)/a; |
| 51 | r[1-first] = (-b + disc)/a; |
| 52 | |
| 53 | return(2); |
| 54 | } |