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agomez |
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#ifndef mathfunc_h
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#define mathfunc_h
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#include "gadget.h" |
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/**
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* \brief This is the value of pi used in the simulation
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*/
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const double pivalue = atan(1.0) * 4.0;
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/**
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* \brief This function will calculate the maximum of 2 numbers (integers)
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* \param a is the first number
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* \param b is the second number
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* \return a if a is greater than b, b otherwise
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*/
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inline int max(int a, int b) {
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return ((a > b) ? a : b);
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}
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/**
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* \brief This function will calculate the maximum of 2 numbers (doubles)
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* \param a is the first number
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* \param b is the second number
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* \return a if a is greater than b, b otherwise
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*/
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inline double max(double a, double b) {
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return ((a > b) ? a : b);
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}
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/**
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* \brief This function will calculate the minimum of 2 numbers (integers)
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* \param a is the first number
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* \param b is the second number
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* \return a if a is less than b, b otherwise
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*/
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inline int min(int a, int b) {
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return ((a < b) ? a : b);
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}
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/**
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* \brief This function will calculate the minimum of 2 numbers (doubles)
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* \param a is the first number
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* \param b is the second number
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* \return a if a is less than b, b otherwise
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*/
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inline double min(double a, double b) {
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return ((a < b) ? a : b);
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}
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/**
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* \brief This function will check to see if a number is very close to zero
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* \param a is the number that is being checked
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* \return 1 if the number is very close to zero, 0 otherwise
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* \note This function replaces 'a == 0' to take account of numerical inaccuracies when calculating the exact value of a double
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*/
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inline int isZero(double a) {
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return ((fabs(a) < verysmall) ? 1 : 0);
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}
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/**
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* \brief This function will check to see if two numbers are equal
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* \param a is the first number that is being checked
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* \param b is the second number that is being checked
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* \return 1 if the two numbers are equal, 0 otherwise
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* \note This function replaces 'a == b' to take account of numerical inaccuracies when calculating the exact value of a double
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*/
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inline int isEqual(double a, double b) {
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return ((fabs(a - b) < verysmall) ? 1 : 0);
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}
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/**
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* \brief This function will check to see if a number is rather small (or zero)
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* \param a is the number that is being checked
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* \return 1 if the number is rather small, 0 otherwise
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*/
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inline int isSmall(double a) {
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return ((fabs(a) < rathersmall) ? 1 : 0);
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}
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/**
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* \brief This function will calculate the value of the logarithm of n factorial
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* \param n is the number that the logfactorial will be calculated for
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* \return the value of log(n!)
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* \note This function is not an ANSI function and so will not compile correctly if gadget is compiled with the \c -ansi flag, unless we include \c \#define \c __GNU_SOURCE in this file
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*/
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inline double logFactorial(double n) {
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return lgamma(n + 1.0);
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}
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/**
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* \brief This function will calculate the value of the exponential of n
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* \param n is the number that the exponential will be calculated for
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* \return the value of exp (n)
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* \note This function replaces 'exp' to return a value in the range 0.0 to 1.0
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*/
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inline double expRep(double n) {
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if (n > verysmall)
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return 1.0;
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else if (n < -25.0)
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return rathersmall;
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return exp(n);
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}
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/**
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* \brief This function will generate a random number in the range 0.0 to 1.0
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* \return random number
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* \note This function generates uniformly-distributed doubles in the range 0.0 to 1.0
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*/
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inline double randomNumber() {
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int r = rand();
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double k = r % 32767;
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return (k / 32767.0);
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}
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ulcessvp |
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/**
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* \brief This function will generate a random number in the range 0.0 to 1.0 from a seed
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* \param seed the seed used to calculate the rando number
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* \return random number
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* \note This function generates uniformly-distributed doubles in the range 0.0 to 1.0
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*/
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ulcessvp |
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inline double randomNumber(unsigned* seed) {
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int r = rand_r(seed);
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double k = r % 32767;
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return (k / 32767.0);
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}
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agomez |
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/**
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* \brief This function will calculate the calculate the effective annual mortality caused by a given predation on a specified population during a timestep
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* \param pred is the number that is removed from the population by the predation
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* \param pop is the population size (before predation)
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* \param t is the inverse of proportion of the year covered by the current timestep
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* \return calculated mortality
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*/
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inline double calcMortality(double pred, double pop, double t) {
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if (pred < verysmall)
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return 0.0;
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else if (pred > pop)
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return verybig;
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return (-log(1.0 - (pred / pop)) * t);
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}
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#endif
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