C source code for poisson distribution?

Answer 1

/*************************************************************************/

/* POISSON3.C */

/* Calculate poisson statistics given average number of occurences */

/* and the value of interest. */

/* Uses the formula P(X=x) = mu^x * e^-mu/x!, for x = 1,2,3...x */

/* NOTICE: Factorial1() is copyrighted by author */

/* FURTHERMORE: Software is provided as is, with no promise of fitness */

/* for use. */

/* comments or questions: p_duke52@Yahoo.com */

/* Have fun... */

/* PAD, May 25, 2008 */

/*************************************************************************/ #include <stdio.h>

#include <math.h> /* protype of "e", exp(x) == exp^x */

#include <conio.h> /* For clrscr() */ /*********************************************************\

// copyrighted by author

// Written by: Jaco van Staden

// Date: 13 July 2002

// Program: Maths Program

// from the file "A_maths_me1067647162002.zip"

// available at Planet Source Code:

// http://www.planet-source-code.com

// changed int to double for size issues

// -- PAD, 5/25/08

\**********************************************************/ double Factorial1 (double a)

{

double answer = 1.0;

while(a>1)

answer *= a--;

return answer;

} int main(void)

{

double result, res1, res2;

double i = 0.0, k = 0.00;

double answer = 0.0; result = res1 = res2 = 0.0; clrscr(); /* makes it easier to see input prompts */ printf("Enter mean: ");

scanf("%lf", &i); printf("Enter value of interest: ");

scanf("%lf", &k); /* factorial of value of interest */ answer = Factorial1(k); /* formula for k */

result = pow(i,k);

res1 = 1/(exp(k));

res2 = (result * res1) / answer; printf("answer is ... : %0.20lf", res2);

return 0;

} /*************************************************************************/

/* POISSON3.C */

/* Calculate poisson statistics given average number of occurences */

/* and the value of interest. */

/* Uses the formula P(X=x) = mu^x * e^-mu/x!, for x = 1,2,3...x */

/* NOTICE: Factorial1() is copyrighted by author */

/* FURTHERMORE: Software is provided as is, with no promise of fitness */

/* for use. */

/* comments or questions: p_duke52@yahoo.com */

/* Have fun... */

/* PAD, May 25, 2008 */

/*************************************************************************/ #include <stdio.h>

#include <math.h> /* protype of "e", exp(x) == exp^x */

#include <conio.h> /* For clrscr() */ /*********************************************************\

// copyrighted by author

// Written by: Jaco van Staden

// Date: 13 July 2002

// Program: Maths Program

// from the file "A_maths_me1067647162002.zip"

// available at Planet Source Code:

// http://www.planet-source-code.com

// changed int to double for size issues

// -- PAD, 5/25/08

\**********************************************************/ double Factorial1 (double a)

{

double answer = 1.0;

while(a>1)

answer *= a--;

return answer;

} int main(void)

{

double result, res1, res2;

double i = 0.0, k = 0.00;

double answer = 0.0; result = res1 = res2 = 0.0; clrscr(); /* makes it easier to see input prompts */ printf("Enter mean: ");

scanf("%lf", &i); printf("Enter value of interest: ");

scanf("%lf", &k); /* factorial of value of interest */ answer = Factorial1(k); /* formula for k */

result = pow(i,k);

res1 = 1/(exp(k));

res2 = (result * res1) / answer; printf("answer is ... : %0.20lf", res2);

return 0;

}