# Use C language to generate Poisson distribution random number instance source code

Source: Internet
Author: User

Helping a friend do a job in graduate management is a simulation of the inventory system, where the retailer's demand is a random number with Poisson distribution. We need to use C language to generate random numbers with Poisson distribution. By looking for materials and programming practices, a simple program is written as follows for your reference.

 The code is as follows: ```Algorithm poisson random number (Knuth ): Init: Let L & larr; exp (& minus; & lambda;), k & larr; 0 and p & larr; 1. Do: K & larr; k + 1. Generate uniform. random number u in [0, 1] and let p & larr; p × u. While p> = L. Return (k & minus; 1 ).```

The code for the Poisson distribution random number in C language is as follows:

 The code is as follows: ```# Include # Include # Include Double U_Random (); Int possion (); Void main () { Double u = U_Random (); Int p = possion (); Printf ("% fn", u ); Printf ("% dn", p ); } Int possion ()/* generates a random number with a Poisson distribution. Lamda is the average number */ { Int Lambda = 20, k = 0; Long double p = 1.0; Long double l = exp (-Lambda);/* it is defined as long double for precision, and exp (-Lambda) is a decimal near 0 */ Printf ("%. 15Lfn", l ); While (p> = l) { Double u = U_Random (); P * = u; K ++; } Return K-1; } Double U_Random ()/* generates a 0 ~ Random number between 1 */ { Double f; Srand (unsigned) time (NULL )); F = (float) (rand () % 100 ); /* Printf ("% fn", f );*/ Return f/100; }```

All the code for this simple inventory simulation: https://github.com/smilejay/c-cpp/tree/master/inventory-simulation

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