Subversion Repositories programming

/* Copyright: Ira W. Snyder
 * Start Date: 2005-09-28
 * End Date: 2005-10-12
 * License: Public Domain
 *
 * Changelog Follows:
 *
 * 2005-09-28:
 * - Added the code to calculate the change in volumes in single
 *   and double precision.
 *
 * 2005-09-29:
 * - Added the code to calculate the volumes in single and double precision.
 * - Added the code to calculate the change in volumes using the surface area
 *   method, in single and double precision.
 *
 * 2005-10-12:
 * - Prettified output.
 * - Code cleanups.
 * - Added "Change in vol" subtraction in Part 1.
 * - Print the radii in Part 2.
 *
 */

#include <cstdio>
#include <cstdlib>
#include <cmath>
using namespace std;

#define PI 3.14159265358979323846264

float volume_single (float radius)
{
    /* Implements:
     * Vol = (4/3) * PI * r^3
     * in single precision. */

    float vol = (4.0F/3.0F) * (float)PI;
    vol *= powf (radius, 3.0);

    return vol;
}

float volume_double (double radius)
{
    /* Implements:
     * Vol = (4/3) * PI * r^3
     * in double precision. */

    double vol = (4.0F/3.0F) * (double)PI;
    vol *= pow (radius, 3.0);

    return vol;
}

float change_volume_single (float rad_old, float rad_new)
{
    /* Implements:
     * Change_in_vol = (4/3) * PI * (r_new - r_old) * (r_new^2 + r_new*r_old + r_old^2)
     * in single precision. */

    float vol = (4.0F/3.0F) * (float)PI;
    vol *= (rad_new - rad_old);
    vol *= (powf (rad_new, 2.0) + (rad_new * rad_old) + powf (rad_old, 2.0));

    return vol;
}

double change_volume_double (double rad_old, double rad_new)
{
    /* Implements:
     * Change_in_vol = (4/3) * PI * (r_new - r_old) * (r_new^2 + r_new*r_old + r_old^2)
     * in double precision. */

    double vol = (4.0F/3.0F) * (double)PI;
    vol *= (rad_new - rad_old);
    vol *= (pow (rad_new, 2.0) + (rad_new * rad_old) + pow (rad_old, 2.0));

    return vol;
}

float approx_change_volume_single (float radius, float r_change)
{
    /* Implements:
     * Change_in_vol = 4 * PI * r_old^2 * r_change
     * in single precision; */

    float vol = 4.0F * (float)PI * powf(radius, 2.0) * r_change;

    return vol;
}

double approx_change_volume_double (double radius, double r_change)
{
    /* Implements:
     * Change_in_vol = 4 * PI * r_old^2 * r_change
     * in double precision; */

    double vol = 4.0F * (double)PI * pow(radius, 2.0) * r_change;

    return vol;
}

int main (void)
{
    /* Constants */
    const float  r_change_single  = 1.0F / 12.0F / 5280.0F; //convert 0.1 inch to miles
    const double r_change_double  = 1.0  / 12.0  / 5280.0;  //convert 0.1 inch to miles
    const double rad_earth_1900   = 4000.0;
    const float  rad_earth_2000_s = rad_earth_1900 + r_change_single;
    const double rad_earth_2000_d = rad_earth_1900 + r_change_double;

    float temp_f1, temp_f2;
    double temp_d1, temp_d2;

    /* Part 1: Volumes in single and double precision */
    printf ("Part 1: Volumes in single and double precision\n");
    printf ("============================================================\n");
    printf ("Single Precision:\n");

    temp_f1 = volume_single (rad_earth_1900);
    printf ("Volume of the Earth in 1900AD: %.20e\n", temp_f1);

    temp_f2 = volume_single (rad_earth_2000_s);
    printf ("Volume of the Earth in 2000AD: %.20e\n", temp_f2);

    printf ("Change in volume: %.20e cubic miles\n\n", temp_f2 - temp_f1);

    printf ("Double Precision:\n");

    temp_d1 = volume_double (rad_earth_1900);
    printf ("Volume of the Earth in 1900AD: %.20e\n", temp_d1);

    temp_d2 = volume_double (rad_earth_2000_d);
    printf ("Volume of the Earth in 2000AD: %.20e\n", temp_d2);

    printf ("Change in volume: %.20e cubic miles\n\n", temp_d2 - temp_d1);

    /* Part 2: Change in volume of the Earth in single and double precision */
    printf ("Part 2: Change in volume of the Earth in single and double precision\n");
    printf ("============================================================\n");
    printf ("Single Precision:\n");

    printf ("Radius of the Earth in 1900AD: %.20e\n", rad_earth_1900);
    printf ("Radius of the Earth in 2000AD: %.20e\n", rad_earth_2000_s);

    temp_f1 = change_volume_single (rad_earth_1900, rad_earth_2000_s);
    printf ("Change in vol = %.20e cubic miles\n\n", temp_f1);

    printf ("Double Precision:\n");

    printf ("Radius of the Earth in 1900AD: %.20e\n", rad_earth_1900);
    printf ("Radius of the Earth in 2000AD: %.20e\n", rad_earth_2000_d);

    temp_d1 = change_volume_double (rad_earth_1900, rad_earth_2000_d);
    printf ("Change in vol = %.20e cubic miles\n\n", temp_d1);

    /* Part 3: Approximation of the change in volume using the surface area method,
     * in single and double precision */
    printf ("Part 3: Approximation of the change in volume of the Earth using\n");
    printf ("the surface area method, in single and double precision\n");
    printf ("============================================================\n");
    printf ("Single Precision:\n");

    temp_f1 = approx_change_volume_single (rad_earth_1900, r_change_single);
    printf ("Change in vol = %.20e cubic miles\n\n", temp_f1);

    printf ("Double Precision:\n");

    temp_d1 = approx_change_volume_double (rad_earth_1900, r_change_double);
    printf ("Change in vol = %.20e cubic miles\n\n", temp_d1);

    return 0;
}