Mercurial > sdl-ios-xcode
view src/video/xbios/SDL_xbios_sb3.h @ 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 | 99210400e8b9 |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2004 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with this library; if not, write to the Free Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Sam Lantinga slouken@libsdl.org */ #include "SDL_config.h" /* ScreenBlaster 3 definitions Patrice Mandin */ #ifndef _SDL_xbios_sb3_h_ #define _SDL_xbios_sb3_h_ /*--- Defines ---*/ #ifndef C_SCPN #define C_SCPN 0x5343504EL #endif #define SCPN_DEV_1BPP 0 #define SCPN_DEV_2BPP 1 #define SCPN_DEV_4BPP 2 #define SCPN_DEV_8BPP 3 #define SCPN_DEV_16BPP 4 extern const int SDL_XBIOS_scpn_planes_device[]; /*--- Types ---*/ typedef struct { unsigned short virtual_width; /* Virtual screen width */ unsigned short virtual_height; /* Virtual screen height */ unsigned short visible_width; /* Visible width */ unsigned short visible_height; /* Visible height */ unsigned short h_pos; /* Horizontal position in virtual screen */ unsigned short v_pos; /* Vertical position in virtual screen */ unsigned short dummy; unsigned long size; /* Size of screen in bytes */ unsigned short device; /* Device number to find planes = getRez() */ /* = Index in scpn_planes_device[] */ } __attribute__ ((packed)) scpn_screeninfo_t; typedef struct { unsigned long magic; /* just a BRA assembler jump */ unsigned short version; void *dummy1; unsigned short ptsout0_1; unsigned short ptsout0_2; unsigned short dummy3; unsigned char date[8]; /* Date of program build */ unsigned char asm_string[30]; /* 10 times the 'ASM' string */ unsigned short dummy4; scpn_screeninfo_t *screen_info; unsigned short dummy6; } __attribute__ ((packed)) scpn_cookie_t; /*--- Function prototypes ---*/ int SDL_XBIOS_SB3Usable(scpn_cookie_t * cookie_scpn); void SDL_XBIOS_SB3Init(_THIS, scpn_cookie_t * cookie_scpn); #endif /* _SDL_xbios_sb3_h_ */ /* vi: set ts=4 sw=4 expandtab: */