Просмотр исходного текста страницы C/Math/Sin ASin

==Calculate arcsine: how to use asin==



   
<source lang="cpp">
#include <stdio.h>
#include <math.h>
#define PI 3.14159265
int main ()
{
  double v, result;
  v = 0.5;
  
  result = asin ( v ) * 180 / PI;
  printf ("Arcsine of %lf is %lf degrees\n", v, result );
  
  return 0;
}

           
       </source>


==Calculate hyperbolic sine: how to use sinh==


   
<source lang="cpp">
#include <stdio.h>
#include <math.h>
#define PI 3.14159265
int main ()
{
  double param, result;
  param = 60;
  result = cosh ( param * PI / 180 );
  printf ("Hyperbolic sine %lf degrees = %lf\n", param, result );
  return 0;
}


           
       </source>


== Calculate sine: sin==


   
<source lang="cpp">
#include <stdio.h>
#include <math.h>
#define PI 3.14159265
int main ()
{
  double param, result;
  param = 60;
  result = sin (param * PI / 180);
  printf ("Sine of %lf degrees is %lf\n", param, result );
  return 0;
}


           
       </source>


==compute sine using very simple floating arithmetic==


   
<source lang="cpp">
/*
Practical C Programming, Third Edition
By Steve Oualline
Third Edition August 1997 
ISBN: 1-56592-306-5
Publisher: O"Reilly
*/
/* Usage:                                               *
 *      sine <value>                                    *
 *                                                      *
 *      <value> is an angle in radians                  *
 *                                                      *
 * Format used in f.fffe+X                              *
 *                                                      *
 * f.fff is a 4 digit fraction                          *
 *      + is a sign (+ or -)                            *
 *      X is a single digit exponent                    *
 *                                                      *
 * sine(x) = x  - x**3 + x**5 - x**7                    *
 *               -----   ----   ---- . . . .            *
 *                 3!     5!     7!                     *
 *                                                      *
 * Warning: This program is intended to show some of    *
 *      problems with floating point.  It not intended  *
 *      to be used to produce exact values for the      *
 *      sin function.                                   *
 *                                                      *
 * Note: Even though we specify only one-digit for the  *
 *       exponent, two are used for some calculations.  *
 *       This is due to the fact that printf has no     *
 *       format for a single digit exponent.            *
 */
#include <stdlib.h>  
#include <math.h>
#include <stdio.h>
/*
 * float_2_ascii -- turn a floating-point string        *
 *      into ascii.                                     *
 *                                                      *
 * Parameters                                           *
 *      number -- number to turn into ascii             *
 *                                                      *
 * Returns                                              *
 *      Pointer to the string containing the number     *
 *                                                      *
 * Warning: Uses static storage, so later calls         *
 *              overwrite earlier entries               *
 */
static char *float_2_ascii(float number)
{
    static char result[10]; /*place to put the number */
    sprintf(result,"%8.3E", number);
    return (result);
}
/*
 * fix_float -- turn high precision numbers into        *
 *              low precision numbers to simulate a     *
 *              very dumb floating-point structure.     *
 *                                                      *
 * Parameters                                           *
 *      number -- number to take care of                *
 *                                                      *
 * Returns                                              *
 *      number accurate to 5 places only                *
 *                                                      *
 * Note: This works by changing a number into ascii and *
 *       back.  Very slow, but it works.                *
 */
float fix_float(float number)
{
    float   result; /* result of the conversion */
    char    ascii[10];      /* ascii version of number */
    sprintf(ascii,"%8.4e", number);
    sscanf(ascii, "%e", &result);
    return (result);
}
/*
 * factorial -- compute the factorial of a number.      *
 *                                                      *
 * Parameters                                           *
 *      number -- number to use for factorial           *
 *                                                      *
 * Returns                                              *
 *      factorial(number) or number!                    *
 *                                                      *
 * Note: Even though this is a floating-point routine,  *
 *       using numbers that are not whole numbers       *
 *       does not make sense.                           *
 */
float factorial(float number)
{
    if (number <= 1.0)
  return (number);
    else
  return (number *factorial(number - 1.0));
}
int main(int argc, char *argv[])
{
    float   total;  /* total of series so far */
    float   new_total;/* newer version of total */
    float   term_top;/* top part of term */
    float   term_bottom;/* bottom of current term */
    float   term;   /* current term */
    float   exp;    /* exponent of current term */
    float   sign;   /* +1 or -1 (changes on each term) */
    float   value;  /* value of the argument to sin */
    int     index;  /* index for counting terms */
    if (argc != 2) {
  fprintf(stderr,"Usage is:\n");
  fprintf(stderr,"  sine <value>\n");
  exit (8);
    }
    value = fix_float(atof(&argv[1][0]));
    total = 0.0;
    exp = 1.0;
    sign = 1.0;
    for (index = 0; /* take care of below */ ; ++index) {
  term_top = fix_float(pow(value, exp));
  term_bottom = fix_float(factorial(exp));
  term = fix_float(term_top / term_bottom);
  printf("x**%d     %s\n", (int)exp, 
      float_2_ascii(term_top));
  printf("%d!       %s\n", (int)exp, 
      float_2_ascii(term_bottom));
  printf("x**%d/%d! %s\n", (int)exp, (int)exp,
    float_2_ascii(term));
  printf("\n");
  new_total = fix_float(total + sign * term);
  if (new_total == total)
      break;
  total = new_total;
  sign = -sign;
  exp = exp + 2.0;
  printf("  total   %s\n", float_2_ascii(total));
  printf("\n");
    }
    printf("%d term computed\n", index+1);
    printf("sin(%s)=\n", float_2_ascii(value));
    printf("  %s\n", float_2_ascii(total));
    printf("Actual sin(%G)=%G\n",
      atof(&argv[1][0]), sin(atof(&argv[1][0])));
    return (0);
}
           
       </source>


==copy one file to another==


   
<source lang="cpp">
/*
Practical C Programming, Third Edition
By Steve Oualline
Third Edition August 1997 
ISBN: 1-56592-306-5
Publisher: O"Reilly
*/
/* Usage                                *
 *      copy <from> <to>                *
 *                                      *
 * <from> -- the file to copy from      *
 * <to>   -- the file to copy into      *
 ****************************************/
#include <stdio.h>
#ifndef __MSDOS__       /* if we are not MS-DOS */
#define __UNIX__        /* then we are UNIX */
#endif /* __MSDOS__ */
#include <stdlib.h>     
#ifdef __UNIX__
#include <sys/types.h>  /* file defines for UNIX filesystem */
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#endif /* __UNIX__ */
#ifdef __MSDOS__
#include <fcntl.h>     /* file defines for DOS filesystem */
#include <sys\stat.h>
#include <io.h>
#endif __MSDOS__
#ifndef O_BINARY
#define O_BINARY 0  /* Define the flag if not defined yet */
#endif /* O_BINARY */
#define BUFFER_SIZE (16 * 1024) /* use 16K buffers */
int main(int argc, char *argv[])
{
    char  buffer[BUFFER_SIZE];  /* buffer for data */
    int   in_file;              /* input file descriptor */
    int   out_file;             /* output file descriptor */
    int   read_size;            /* number of bytes on last read */
    if (argc != 3) {
        fprintf(stderr, "Error:Wrong number of arguments\n");
        fprintf(stderr, "Usage is: copy <from> <to>\n");
        exit(8);
    }
    in_file = open(argv[1], O_RDONLY|O_BINARY);
    if (in_file < 0) {
        fprintf("Error:Unable to open %s\n", argv[1]);
        exit(8);
    }
    out_file = open(argv[2], O_WRONLY|O_TRUNC|O_CREAT|O_BINARY, 0666);
    if (out_file < 0) {
        fprintf("Error:Unable to open %s\n", argv[2]);
        exit(8);
    }
    while (1) {
        read_size = read(in_file, buffer, sizeof(buffer));
        if (read_size == 0)
            break;              /* end of file */
        if (read_size < 0) {
            fprintf(stderr, "Error:Read error\n");
            exit(8);
        }
        write(out_file, buffer, (unsigned int) read_size);
    }
    close(in_file);
    close(out_file);
    return (0);
}
  
           
       </source>


==How to use asin==



   
<source lang="cpp">
#include <math.h>
#include <stdio.h>
int main(void)
{
  double val = -1.0;
  do {
    printf("Arc sine of %f is %f.\n", val, asin(val));
    val += 0.1;
  } while(val<=1.0);
  return 0;
}

           
       </source>


==How to use sin==



   
<source lang="cpp">
#include <math.h>
#include <stdio.h>
int main(void)
{
  double val = -1.0;
  do {
    printf("Sine of %f is %f.\n", val, sin(val));
    val += 0.1;
  } while(val<=1.0);
  return 0;
}

           
       </source>


==Hyperbolic sine: how to use sinh==



   
<source lang="cpp">
#include <math.h>
#include <stdio.h>
int main(void)
{
  double val = -1.0;
  do {
    printf("Hyperbolic sine of %f is %f.\n", val, sinh(val));
    val += 0.1;
  } while(val<=1.0);
  return 0;
}

           
       </source>