920428-2.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

double sin(double x);
double cos(double x);
double tan(double x);
double asin(double x);
double acos(double x);
double atan(double x);
double atan2(double y, double x);
double sinh(double x);
double cosh(double x);
double tanh(double x);
double exp(double x);
double expm1(double x);
double log(double x);
double log10(double x);
double log1p(double x);
double pow(double x, double y);
double sqrt(double x);
double cbrt(double x);
double ceil(double x);
double floor(double x);
double fabs(double x);
double frexp(double value, int *eptr);
double ldexp(double value, int exp);
double modf(double value, double *iptr);
double erf(double x);
double erfc(double x);
double atof(const char *nptr);
double hypot(double x, double y);
double lgamma(double x);
double j0(double x);
double j1(double x);
double jn(int n, double x);
double y0(double x);
double y1(double x);
double yn(int n, double x);
extern struct _iobuf {
 int _cnt;
 char *_ptr;
 char *_base;
 int _bufsiz;
 short _flag;
 char _file;
} _iob[];
typedef unsigned long size_t;
typedef char *va_list;
struct _iobuf *fopen(const char *filename, const char *type);
struct _iobuf *freopen(const char *filename, const char *type, struct _iobuf *stream);
struct _iobuf *fdopen(int fildes, const char *type);
struct _iobuf *popen(const char *command, const char *type);
int pclose(struct _iobuf *stream);
int fflush(struct _iobuf *stream);
int fclose(struct _iobuf *stream);
int remove(const char *path);
int rename(const char *from, const char *to);
struct _iobuf *tmpfile(void);
char *tmpnam(char *s);
int setvbuf(struct _iobuf *iop, char *buf, int type, size_t size);
int setbuf(struct _iobuf *stream, char *buf);
int setbuffer(struct _iobuf *stream, char *buf, size_t size);
int setlinebuf(struct _iobuf *stream);
int fprintf(struct _iobuf *stream, const char *format, ...);
int printf(const char *format, ...);
char *sprintf(char *s, const char *format, ...);
int vfprintf(struct _iobuf *stream, const char *format, va_list arg);
int vprintf(const char *format, va_list arg);
int vsprintf(char *s, const char *format, va_list arg);
int fscanf(struct _iobuf *stream, const char *format, ...);
int scanf(const char *format, ...);
int sscanf(char *s, const char *format, ...);
int fgetc(struct _iobuf *stream);
int getw(struct _iobuf *stream);
char *fgets(char *s, int n, struct _iobuf *stream);
char *gets(char *s);
int fputc(int c, struct _iobuf *stream);
int putw(int w, struct _iobuf *stream);
int fputs(const char *s, struct _iobuf *stream);
int puts(const char *s);
int ungetc(int c, struct _iobuf *stream);
int fread(void *ptr, size_t size, size_t count, struct _iobuf *iop);
int fwrite(const void *ptr, size_t size, size_t count, struct _iobuf *iop);
int fseek(struct _iobuf *stream, long offset, int ptrname);
long ftell(struct _iobuf *stream);
void rewind(struct _iobuf *stream);
int fgetpos(struct _iobuf *stream, long *pos);
int fsetpos(struct _iobuf *stream, const long *pos);
void perror(const char *s);
typedef unsigned char byte;
typedef unsigned char uchar;
typedef unsigned short ushort;
typedef unsigned int uint;
typedef unsigned long ulong;
typedef unsigned char u_char;
typedef unsigned short u_short;
typedef unsigned int u_int;
typedef unsigned long u_long;
typedef unsigned short ushort_;
typedef struct _physadr { int r[1]; } *physadr;
typedef struct label_t {
 int val[11];
} label_t;
typedef struct _quad { long val[2]; } quad;
typedef long daddr_t;
typedef char * caddr_t;
typedef u_long ino_t;
typedef long swblk_t;
typedef long time_t;
typedef short dev_t;
typedef long off_t;
typedef u_short uid_t;
typedef u_short gid_t;
typedef signed char prio_t;
typedef long fd_mask;
typedef struct fd_set {
 fd_mask fds_bits[(((256 )+(( (sizeof(fd_mask) * 8 ) )-1))/( (sizeof(fd_mask) * 8 ) )) ];
} fd_set;
typedef struct qhdr {
 struct qhdr *link, *rlink;
} *queue_t;
typedef char *ptr_ord_t;
typedef double floatp;
typedef char *(*proc_alloc_t)(unsigned num_elements, unsigned element_size, const char *client_name );
typedef void (*proc_free_t)(char *data, unsigned num_elements, unsigned element_size, const char *client_name );
extern struct _iobuf *gs_out;
typedef struct gs_point_s {
 double x, y;
} gs_point;
typedef struct gs_int_point_s {
 int x, y;
} gs_int_point;
typedef struct gs_rect_s {
 gs_point p, q;
} gs_rect;
typedef struct gs_int_rect_s {
 gs_int_point p, q;
} gs_int_rect;
typedef struct gs_state_s gs_state;
typedef struct {
 proc_alloc_t alloc;
 proc_free_t free;
} gs_memory_procs;
char *gs_malloc(uint, uint, const char * );
void gs_free(char *, uint, uint, const char * );
extern char gs_debug[128];
extern int gs_log_error(int, const char *, int );
typedef long fixed;
typedef struct gs_fixed_point_s {
 fixed x, y;
} gs_fixed_point;
typedef struct gs_fixed_rect_s {
 gs_fixed_point p, q;
} gs_fixed_rect;
typedef struct gs_matrix_s {
 long _xx; float xx; long _xy; float xy; long _yx; float yx; long _yy; float yy; long _tx; float tx; long _ty; float ty;
} gs_matrix;
void gs_make_identity(gs_matrix * );
int gs_make_translation(floatp, floatp, gs_matrix * ),
 gs_make_scaling(floatp, floatp, gs_matrix * ),
 gs_make_rotation(floatp, gs_matrix * );
int gs_matrix_multiply(const gs_matrix *, const gs_matrix *, gs_matrix * ),
 gs_matrix_invert(const gs_matrix *, gs_matrix * ),
 gs_matrix_rotate(const gs_matrix *, floatp, gs_matrix * );
int gs_point_transform(floatp, floatp, const gs_matrix *, gs_point * ),
 gs_point_transform_inverse(floatp, floatp, const gs_matrix *, gs_point * ),
 gs_distance_transform(floatp, floatp, const gs_matrix *, gs_point * ),
 gs_distance_transform_inverse(floatp, floatp, const gs_matrix *, gs_point * ),
 gs_bbox_transform_inverse(gs_rect *, gs_matrix *, gs_rect * );
typedef struct gs_matrix_fixed_s {
 long _xx; float xx; long _xy; float xy; long _yx; float yx; long _yy; float yy; long _tx; float tx; long _ty; float ty;
 fixed tx_fixed, ty_fixed;
} gs_matrix_fixed;
extern void gs_update_matrix_fixed(gs_matrix_fixed * );
int gs_point_transform2fixed(gs_matrix_fixed *, floatp, floatp, gs_fixed_point * ),
 gs_distance_transform2fixed(gs_matrix_fixed *, floatp, floatp, gs_fixed_point * );
typedef struct {
 long xx, xy, yx, yy;
 int skewed;
 int shift;
 int max_bits;
 fixed round;
} fixed_coeff;

typedef enum {
 gs_cap_butt = 0,
 gs_cap_round = 1,
 gs_cap_square = 2
} gs_line_cap;
typedef enum {
 gs_join_miter = 0,
 gs_join_round = 1,
 gs_join_bevel = 2
} gs_line_join;
gs_state *gs_state_alloc(proc_alloc_t, proc_free_t );
int gs_state_free(gs_state * );
int gs_gsave(gs_state * ),
 gs_grestore(gs_state * ),
 gs_grestoreall(gs_state * );
gs_state *gs_gstate(gs_state * );
int gs_currentgstate(gs_state * , const gs_state * ),
 gs_setgstate(gs_state * , const gs_state * );
gs_state *gs_state_swap_saved(gs_state *, gs_state * );
void gs_state_swap(gs_state *, gs_state * );
int gs_initgraphics(gs_state * );
typedef struct gx_device_s gx_device;
int gs_flushpage(gs_state * );
int gs_copypage(gs_state * );
int gs_output_page(gs_state *, int, int );
int gs_copyscanlines(gx_device *, int, byte *, uint, int *, uint * );
gx_device * gs_getdevice(int );
int gs_copydevice(gx_device **, gx_device *, proc_alloc_t );
int gs_makeimagedevice(gx_device **, gs_matrix *, uint, uint, byte *, int, proc_alloc_t );
void gs_nulldevice(gs_state * );
int gs_setdevice(gs_state *, gx_device * );
gx_device * gs_currentdevice(gs_state * );
const char * gs_devicename(gx_device * );
void gs_deviceinitialmatrix(gx_device *, gs_matrix * );
int gs_closedevice(gx_device * );
int gs_setlinewidth(gs_state *, floatp );
float gs_currentlinewidth(const gs_state * );
int gs_setlinecap(gs_state *, gs_line_cap );
gs_line_cap gs_currentlinecap(const gs_state * );
int gs_setlinejoin(gs_state *, gs_line_join );
gs_line_join gs_currentlinejoin(const gs_state * );
int gs_setmiterlimit(gs_state *, floatp );
float gs_currentmiterlimit(const gs_state * );
int gs_setdash(gs_state *, const float *, uint, floatp );
uint gs_currentdash_length(const gs_state * );
int gs_currentdash_pattern(const gs_state *, float * );
float gs_currentdash_offset(const gs_state * );
int gs_setflat(gs_state *, floatp );
float gs_currentflat(const gs_state * );
int gs_setstrokeadjust(gs_state *, int );
int gs_currentstrokeadjust(const gs_state * );
typedef enum {
 gs_color_space_DeviceGray = 0,
 gs_color_space_DeviceRGB,
 gs_color_space_DeviceCMYK
} gs_color_space;
typedef struct gs_color_s gs_color;
extern const uint gs_color_sizeof;
int gs_setgray(gs_state *, floatp );
float gs_currentgray(gs_state * );
int gs_sethsbcolor(gs_state *, floatp, floatp, floatp ),
 gs_currenthsbcolor(gs_state *, float [3] ),
 gs_setrgbcolor(gs_state *, floatp, floatp, floatp ),
 gs_currentrgbcolor(gs_state *, float [3] );
int gs_currentcolorspace(gs_state *, gs_color_space * );
typedef float (*gs_transfer_proc)(gs_state *, floatp );
int gs_settransfer(gs_state *, gs_transfer_proc ),
 gs_settransfer_remap(gs_state *, gs_transfer_proc, int );
gs_transfer_proc gs_currenttransfer(gs_state * );
int gs_setcolortransfer(gs_state *, gs_transfer_proc ,
 gs_transfer_proc , gs_transfer_proc ,
 gs_transfer_proc ),
 gs_setcolortransfer_remap(gs_state *, gs_transfer_proc ,
 gs_transfer_proc , gs_transfer_proc ,
 gs_transfer_proc , int );
void gs_currentcolortransfer(gs_state *, gs_transfer_proc [4] );
int gs_setscreen(gs_state *, floatp, floatp, float (*)(floatp, floatp ) );
int gs_currentscreen(gs_state *, float *, float *, float (**)(floatp, floatp ) );
int gs_sethalftonephase(gs_state *, int, int );
int gs_currenthalftonephase(gs_state *, gs_int_point * );
typedef struct gs_screen_enum_s gs_screen_enum;
extern const uint gs_screen_enum_sizeof;
int gs_screen_init(gs_screen_enum *, gs_state *, floatp, floatp );
int gs_screen_currentpoint(gs_screen_enum *, gs_point * );
int gs_screen_next(gs_screen_enum *, floatp );