Mercurial > sdl-ios-xcode
view test/torturethread.c @ 2752:edd2839b36f7
http://sources.redhat.com/ml/newlib/2002/msg00230.html
Stephen L Moshier wrote:
>
> pow(x,y) returns 0 when x is very close to -1.0 and y is very large.
> The following test program prints
>
> pow(1.0000000000000002e+00 4.5035996273704970e+15) = 2.7182818284590455e+00
> pow(-1.0000000000000002e+00 4.5035996273704970e+15) =0.0000000000000000e+00
> pow(9.9999999999999978e-01 4.5035996273704970e+15) = 3.6787944117144222e-01
> pow(-9.9999999999999978e-01 4.5035996273704970e+15) = 0.0000000000000000e+00
>
> which is incorrect for the negative arguments raised to an odd integer
> power.
>
> -----
> double pow (double, double);
>
> int
> main ()
> {
> double x, y, z;
>
> x = 1.0 + pow (2.0, -52.0);
> y = 1.0 + pow (2.0, 52.0);
> z = pow (x, y);
> printf ("pow(%.16e %.16e) = %.16e\n", x, y, z);
> x = -x;
> z = pow (x, y);
> printf ("pow(%.16e %.16e) = %.16e\n", x, y, z);
> x = 1.0 - pow (2.0, -52.0);
> z = pow (x, y);
> printf ("pow(%.16e %.16e) = %.16e\n", x, y, z);
> x = -x;
> z = pow (x, y);
> printf ("pow(%.16e %.16e) = %.16e\n", x, y, z);
> }
> -----
>
> Here is a patch for newlib/libm/math/epow.c:
Patch checked in and duplicated for ef_pow.c. Thanks.
-- Jeff J.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Mon, 15 Sep 2008 04:31:30 +0000 |
parents | c121d94672cb |
children |
line wrap: on
line source
/* Simple test of the SDL threading code */ #include <stdio.h> #include <stdlib.h> #include <signal.h> #include <string.h> #include "SDL.h" #include "SDL_thread.h" #define NUMTHREADS 10 static char volatile time_for_threads_to_die[NUMTHREADS]; /* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */ static void quit(int rc) { SDL_Quit(); exit(rc); } int SDLCALL SubThreadFunc(void *data) { while (!*(int volatile *) data) { ; /*SDL_Delay(10); *//* do nothing */ } return 0; } int SDLCALL ThreadFunc(void *data) { SDL_Thread *sub_threads[NUMTHREADS]; int flags[NUMTHREADS]; int i; int tid = (int) (uintptr_t) data; fprintf(stderr, "Creating Thread %d\n", tid); for (i = 0; i < NUMTHREADS; i++) { flags[i] = 0; sub_threads[i] = SDL_CreateThread(SubThreadFunc, &flags[i]); } printf("Thread '%d' waiting for signal\n", tid); while (time_for_threads_to_die[tid] != 1) { ; /* do nothing */ } printf("Thread '%d' sending signals to subthreads\n", tid); for (i = 0; i < NUMTHREADS; i++) { flags[i] = 1; SDL_WaitThread(sub_threads[i], NULL); } printf("Thread '%d' exiting!\n", tid); return 0; } int main(int argc, char *argv[]) { SDL_Thread *threads[NUMTHREADS]; int i; /* Load the SDL library */ if (SDL_Init(0) < 0) { fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError()); return (1); } signal(SIGSEGV, SIG_DFL); for (i = 0; i < NUMTHREADS; i++) { time_for_threads_to_die[i] = 0; threads[i] = SDL_CreateThread(ThreadFunc, (void *) (uintptr_t) i); if (threads[i] == NULL) { fprintf(stderr, "Couldn't create thread: %s\n", SDL_GetError()); quit(1); } } for (i = 0; i < NUMTHREADS; i++) { time_for_threads_to_die[i] = 1; } for (i = 0; i < NUMTHREADS; i++) { SDL_WaitThread(threads[i], NULL); } SDL_Quit(); return (0); }