三次自然样条插值编程

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1、//Čý´Î×ÔČťŃůĚő˛ĺÖľąŕłĚ.cpp:Definestheentrypointfortheconsoleapplication.////#include"stdafx.h"#include"stdio.h"voidGetValueSpline(intn,doublex[],doubley[],doubledy[],doubleddy[],intm,doublet[],doublez[],doubledz[],doubleddz[]){inti,j;doubleh0,h1,alpha,beta,g,*s;h0=x[1]-x[0];s[0

2、]=3.0*(y[1]-y[0])/2.0*h0-ddy[0]*h0/4.0;for(j=1;j<=n-2;j++){h1=x[j+1]-x[j];alpha=h0/(h0+h1);beta=(1.0-alpha)*(y[j]-y[j-1])/h0;beta=3.0*(beta+alpha*(y[j+1]-y[j]))/h1;dy[j]=-alpha/(2.0+(1.0-alpha))*dy[j-1];s[j]=s[j-1]/(2.0+(1.0-alpha))*dy[j-1];h0=h1;}dy[n-1]=(3.0*(y[n-1]-y[n-2])/h

3、1+ddy[n-1]*h1/2.0-s[n-2])/(2.0+dy[n-2]);for(j=n-2;j>=0;j--)dy[j]=dy[j]*dy[j+1]+s[j];for(j=0;j<=n-2;j++)s[j]=x[j+1]-x[j];for(j=0;j<=n-2;j++){h1=s[j]*s[j];ddy[j]=6.0*(y[j+1]-y[j])/h1-2.0*(2.0*dy[j]+dy[j+1])/s[j];}h1=s[n-2]*s[n-2];ddy[n-1]=6.0*(y[n-2]-y[n-1])/h1+2.0*(2.0*dy[n-1]+d

4、y[n-2])/s[n-2];g=0.0;for(i=0;i<=n-2;i++){h1=0.5*s[i]*(y[i]+y[i+1]);h1=h1-s[i]*s[i]*s[i]*(ddy[i]+ddy[i+1])/24.0;g=g+h1;}for(j=0;j<=m-1;j++){if(t[j]>=x[n-1])i=n-2;else{i=0;while(t[j]>x[i+1])i=i+1;}h1=(x[i+1]-t[j])/s[i];h0=h1*h1;z[j]=(3.0*h0-2.0*h0*h1)*y[i];z[j]=z[j]+s[i]*(h0-h0*h

5、1)*dy[i];dz[j]=6.0*(h0-h1)*y[i]/s[i];dz[j]=dz[j]+(3.0*h0-2.0*h1)*dy[i];ddz[j]=(6.0-12.0*h1)*y[i]/(s[i]*s[i]);ddz[j]=ddz[j]+(2.0-6.0*h1)*dy[i]/s[i];h1=(t[j]-x[i])/s[i];h0=h1*h1;z[j]=z[j]+(3.0*h0-2.0*h0*h1)*y[i+1];z[j]=z[j]-s[i]*(h0-h0*h1)*dy[i+1];dz[j]=dz[j]-6.0*(h0-h1)*y[i+1]/s

6、[i];dz[j]=dz[j]+(3.0*h0-2.0*h1)*dy[i+1];ddz[j]=ddz[j]+(6.0-12.0*h1)*y[i+1]/(s[i]*s[i]);ddz[j]=ddz[j]-(2.0-6.0*h1)*dy[i+1]/s[i];for(i=0;i<4;i++);{printf("Ö¸ś¨˛ĺÖľľăČý´Î×ÔČťŃůĚő˛ĺ־ҝ˝×ľźĘýÖľśţ˝×ľźĘýÖľ");printf("t(i)z(i)dz(i)ddz(i)");printf("%f%f%f%f",t[i],z[i],dz[i],ddz[i]

7、);}//delete[]s;//return(g);}}voidmain(){inti;doublex[5],y[5],dy[5],ddy[5];doublet[4],z[4],dz[4],ddz[4];printf("ÇëĘäČëÎĺ×éÔĘźĘýžÝ:");for(i=0;i<5;i++){printf("x(%d)=",i);scanf("%f",&x[i]);printf("y(%d)=",i);scanf("%f",&y[i]);}printf("ÇëĘäČë˛ĺÖľľăĘýžÝ:");for(i=0;i<4;i++){pri

8、ntf("t(%d)=",i);scanf("%f",&t[i]);}GetValueSpline(5,