- 401 名前：デフォルトの名無しさん mailto:sage [2007/11/12(月) 22:22:09 ]
- >>394
#include<stdio.h>
#include<math.h>
typedef double (*SingleFun)( double );
double newton(SingleFun fun,SingleFun fprime, double x)
{
double fx;
double fp;
double xprev;
do
{
fx = fun(x);
fp = fprime(x);
if(fp == 0) fp = 1;
xprev = x;
x -= fx / fp;
} while( x != xprev );
return x;
}
double fN(double N) { return 10.0 * N * log( N ) - 2*N*N; }
double dfdN(double N) { return 10.0 * log( N ) - 4.0 * N + 10.0; }
int main(void)
{
double res = newton( fN, dfdN, 1.0 );
printf("result = %1lf\n",res );
printf("10Nlog(N) > 2N^2 is true for N > %lf\n",res);
return 0;
}
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