mt.c File Reference

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#include "mt.h"

Include dependency graph for mt.c:

Go to the source code of this file.

Macros
#define	MAX_ITRTN_NEWTON_METHOD   30
	ニュートン法で解を求める際の，最大繰り返し回数．

Functions
double	power (double x, double y)
double	fact (int n)
double	perm (int n, int m)
double	comb (int n, int m)
int	newton_method (PTR_DFFUNC func, PTR_DFFUNC dfunc, double *t0, double eps)
	ニュートン法で解を求める

Variables
double	EPS = 1.0e-6

Detailed Description

Author

Fumi.Iseki (C)

Definition in file mt.c.

Macro Definition Documentation

MAX_ITRTN_NEWTON_METHOD

#define MAX_ITRTN_NEWTON_METHOD   30

Definition at line 79 of file mt.c.

Referenced by newton_method().

Function Documentation

comb()

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 64 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;
}

fact()

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 30 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;
}

newton_method()

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 95 of file mt.c.

{
    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;
}

References MAX_ITRTN_NEWTON_METHOD, and Xabs.

perm()

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 45 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;
}

power()

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 17 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));
}

Variable Documentation

EPS

double EPS = 1.0e-6

Definition at line 9 of file mt.c.

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