C语言解题经典程序(2)

totoerer · 发表于 2004-5-15 07:49:47

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center" align=center>正割法求方程的根 YUNJIROT.C<

23pt; mso-line-height-rule: exactly">#include<math.h><

23pt; mso-line-height-rule: exactly">#include<stdio.h>double f(double x){ return(x+log(x)-2.0); } double ca_root(double x0,double x1,double eps){int n=1; double x2,fx0,fx1;fx0=f(x0);while(n<800) { fx1=f(x1); x2=x1-fx1/(fx1-fx0)*(x1-x0); if(fabs(x2-x1)<eps)break; x0=x1;fx0=fx1;x1=x2;n++; }return(x2);} main(){double root, eps=1.0e-12;root=ca_root(1.0,2.0,eps);printf("\nThe root =%14.12lf",root);}经过6次循环，计算结果为：1.557145598998

totoerer · 发表于 2004-5-15 07:50:13

<

center" align=center>/*最优梯度法求多元函数的极小值 TIDU.C */<

>#include<conio.h><

>#include<math.h>#include<stdio.h>#define N 2int j; double x[N];double f(double x[]){double fxy;fxy=x[0]-x[1]+2.0*x[0]*x[0]+2.0*x[0]*x[1]+x[1]*x[1]+log(1.0+x[1]*x[1]);return(fxy);}void grad(double x[],double g[]) { g[0]=4.0*x[0]+2.0*x[1]+1.0; g[1]=2.0*x[0]+2.0*x[1]-1.0+2.0*x[1]/(1.0+x[1]*x[1]); }double fun(double x[],double g[],double lbt){int i; double x2[N];for(i=0;i<N;i++) x2=x-lbt*g;return(f(x2));}double ca_min(double x[],double g[],double eps){double a,b,c,x1,x2,x3,f1,f2,f3;a=-2.0; b=2.0; c=(b-a)*0.25; x1=a+c; f1=fun(x,g,x1);x2=x1+c; f2=fun(x,g,x2); x3=x2+c; f3=fun(x,g,x3);for(;;) { if(f1<=f2&&f1<f3) { b=x2;x2=x1;f2=f1; } else if(f3<=f2&&f3<f1) { a=x2;x2=x3;f2=f3; } else { a=x1;b=x3; } c=(b-a)*0.25; if(fabs(c)<eps)break; x1=a+c;f1=fun(x,g,x1); x3=x2+c;f3=fun(x,g,x3); }return(x2);} void tidufa(double x0[],double eps){int i; unsigned k=0;double lbt,f1,f2,x1[N],g[N];f1=f(x0);while(k<100) { grad(x0,g); lbt=ca_min(x0,g,eps*0.1); /*printf("\nlbt=%g \n",lbt);*/ for(i=0;i<N;i++)x1=x0-lbt*g; f2=f(x1); for(i=0;i<N;i++)x0=x1; if(fabs(f2-f1)<eps) { printf("f2-f1<eps k=%d",k); break; } /*printf("k=%d x1=%15.14lf x2=%15.14lf",k,x1[0],x1[1]);*/ f1=f2;k++; }} main(){int i;double x0[N],eps=1.0e-015;x0[0]=1.0;x0[1]=2.0;tidufa(x0,eps); for(i=0;i<N;i++)printf("\nx[%d] = %12.10lf ",i,x0);printf("\nf(X) = %12.10lf ",f(x0);}

totoerer · 发表于 2004-5-15 07:50:38

<

17pt; TEXT-ALIGN: center; mso-line-height-rule: exactly" align=center>/*改进坐标轮换法求多元函数的极小值 DIRECT.C */<

17pt; mso-line-height-rule: exactly"> <

17pt; mso-line-height-rule: exactly">#include<conio.h>#include<math.h>#include<stdio.h>#define N 2 int j;double x[N]; double fun(double x[]){double fxy,t,d;t=x[0]-2.0;d=x[0]-2.0*x[1];fxy=t*t*t*t+d*d;return(fxy);} double fx(double y[],double lbt){int i;for(i=0;i<N;i++)x=y;x[j]=y[j]+lbt;return(fun(x));} double fy(double y[],double lbt){int i;double x2[2];for(i=0;i<N;i++)x2=x+lbt*y;return(fun(x2));} double ca_min(double a,double b,double eps,\double (*fun)(),double y[]){double c;double x1,x2,x3,f1,f2,f3;c=(b-a)*0.25;x1=a+c;f1=fun(y,x1);x2=x1+c;f2=fun(y,x2);x3=x2+c;f3=fun(y,x3);for(;;) { if(f1<=f2&&f1<f3) { b=x2;x2=x1;f2=f1; } else if(f3<=f2&&f3<f1) { a=x2;x2=x3;f2=f3; } else { a=x1;b=x3; } c=(b-a)*0.25; if(fabs(c)<eps)break; x1=a+c;f1=fun(y,x1); x3=x2+c;f3=fun(y,x3); }return(x2);} int direct(double x0[],double eps){int i;unsigned k=0;double lbt,px;double x1[N],y[N];for(i=0;i<N;i++)y=x0;while(k<200) { for(j=0;j<N;j++) { lbt=ca_min(-1.0,1.0,eps*0.01,fx,y); y[j]=y[j]+lbt; } px=0.0; for(i=0;i<N;i++) { x=x1=y; printf("x[%d]=%15.14lf ",i,x); y=x1-x0; x0=x1; px+=(y*y); } if(px<eps)break; lbt=ca_min(-2.0,2.0,eps,fy,y); printf("k=%d lbt=%g \n",k,lbt); for(i=0;i<N;i++)y=x1+lbt*y; k++; }return(1);} main(){int i;double x0[2],eps=1.0e-012;x0[0]=0.0;x0[1]=0.0;direct(x0,eps); for(i=0;i<N;i++) printf("\nx[%d] = %18.16lf ",i,x0);}

shanglei · 发表于 2004-8-3 18:02:22

我正缺这个，真是救星，THANK YOU

loveshumo · 发表于 2004-8-21 02:55:44

<

>草你吗<

>什么够日的程序

loveshumo · 发表于 2004-8-21 02:56:34

[em06]

mengduan · 发表于 2004-8-21 06:33:30

高手,真是高手,只是没有我要用的!!!

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