| Revision: | 2.5 |
| Committed: | Thu Jul 17 09:21:29 2003 UTC (20 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. |
| # | User | Rev | Content |
|---|---|---|---|
| 1 | greg | 1.1 | #ifndef lint |
| 2 | schorsch | 2.5 | static const char RCSid[] = "$Id: zeroes.c,v 2.4 2003/02/25 02:47:22 greg Exp $"; |
| 3 | greg | 1.1 | #endif |
| 4 | /* | ||
| 5 | * zeroes.c - compute roots for various equations. | ||
| 6 | * | ||
| 7 | greg | 2.3 | * External symbols declared in standard.h |
| 8 | */ | ||
| 9 | |||
| 10 | greg | 2.4 | #include "copyright.h" |
| 11 | greg | 1.1 | |
| 12 | |||
| 13 | greg | 2.2 | #include <math.h> |
| 14 | greg | 1.1 | |
| 15 | greg | 2.2 | #include "fvect.h" |
| 16 | schorsch | 2.5 | #include "rtmath.h" |
| 17 | greg | 2.2 | |
| 18 | greg | 1.1 | 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 | } |