Lib/mt.h File Reference

数学関数ヘッダ mt.h More...

#include "common.h"
#include <math.h>

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Typedefs
typedef double(*	PTR_DFFUNC )(double)
	ニュートン法で解を求める場合の関数の型
Functions
double	comb (int n, int i)
double	perm (int n, int i)
double	fact (int n)
double	power (double x, double y)
int	newton_method (PTR_DFFUNC fn, PTR_DFFUNC df, double *t, double e)
	ニュートン法で解を求める
Variables
double	EPS

---

Detailed Description

Author:

Fumi.Iseki (C)

Definition in file mt.h.

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Typedef Documentation

typedef double(* PTR_DFFUNC)(double)

Definition at line 29 of file mt.h.

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Function Documentation

double comb	(	int	n,
		int	m
	)

double comb(int n, int m)

コンビネーション nCm を計算する．

Definition at line 77 of file mt.c.

{
    int    i;
    double c, p;

    if (m>n || n<=0 || m<=0) return 0.;

    p = c = 1.0;
    for (i=n-m+1; i<=n; i++) p = p*(double)i;
    for (i=1;     i<=m; i++) c = c*(double)i;

    return p/c;
}

double fact

(

int

n

)

double fact(int n)

nの階乗 n! を計算する．n>0 でない場合は 1.0 を返す．

Definition at line 39 of file mt.c.

{
    int    i;
    double ret = 1.0;

    if (n>0) for (i=1; i<=n; i++)  ret = ret*(double)i;
    return ret;
}

int newton_method	(	PTR_DFFUNC	func,
		PTR_DFFUNC	dfunc,
		double *	t0,
		double	eps
	)

int newton_method(PTR_DFFUNC func, PTR_DFFUNC dfunc, double* t0, double eps)

ニュートン法で func()==0 の点を求める．
関数の形は double func(double)

Parameters:

	func	double func(double) 型の関数へのポインタ
	dfunc	func()の導関数へのポインタ．
[in,out]	t0	in: 探索開始点（xの初期値）, out: 解．
	eps	誤差．1に対して 1.0e-8 など．

Returns:

解を求めるまでの繰り返し回数．0 の場合は失敗．

See also:

PTR_DFFUNC, MAX_ITRTN_NEWTON_METHOD

Definition at line 109 of file mt.c.

References MAX_ITRTN_NEWTON_METHOD, and Xabs.

{
    double tt  = *t0;
    double ff  = (*func)(tt);

    int n = 1;
    while (n<MAX_ITRTN_NEWTON_METHOD && Xabs(ff)>eps) {
        //
        double df = (*dfunc)(tt);
        if (Xabs(df)<eps) return 0;

        tt = tt - ff/df;
        ff = (*func)(tt);
        n++;
    }

    if (n==MAX_ITRTN_NEWTON_METHOD) return 0;
    *t0 = tt;
    return n;
}

double perm	(	int	n,
		int	m
	)

double perm(int n, int m)

パームテーション nPm を計算する．

Definition at line 56 of file mt.c.

{
    int    i;
    double p;

    if (m>n || n<=0 || m<=0) return 0.;

    p = 1.0;
    for (i=n-m+1; i<=n; i++) p = p*(double)i;

    return p;
}

double power	(	double	x,
		double	y
	)

double power(double x, double y)

xの y乗 x^yを計算する．

Definition at line 24 of file mt.c.

{
    if (y==0.0)      return 1.0;
    else if (x==0.0) return 0.0;
    else return exp((y)*log(x));
}

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Variable Documentation

double EPS

Definition at line 14 of file mt.c.

Referenced by topola(), unit_ivector(), and unit_vector().