?? d2r4.cpp
字號:
# include<iostream.h>
# include<math.h>
# include<iomanip.h>
void main()
{
//program d2r4
//driver for routine splint,which calls spline
int nfunc,i,np;
double xa[11], ya[11], y2[11],pi,yp1,ypn,x,f,y;
np = 10;
pi = 3.141593;
for( nfunc = 1; nfunc<=2; nfunc++)
{
if (nfunc == 1 )
{
cout<<endl;
cout<<"Sine function from 0 to pi"<<endl;
for (i = 1;i<=np;i++)
{
xa[i] = double(i * pi) /double( np);
ya[i] = sin(xa[i]);
}
yp1 = cos(xa[1]);
ypn = cos(xa[np]);
}
else
{
if (nfunc == 2)
{
cout<<endl;
cout<<"Exponential function from 0 to 1"<<endl;
for (i = 1;i<=np;i++)
{
xa[i] = double(1* i) /double(np);
ya[i] = exp(xa[i]);
}
yp1 = exp(xa[1]);
ypn = exp(xa[np]);
}
}
//call spline to get second derivatives
spline(xa, ya, np, yp1, ypn, y2);
//call splint for interpolations
cout<< " x f(x) interpolation"<<endl;
for (i = 1; i<=10; i++)
{
if (nfunc == 1)
{
x = (-0.05 + double(i) / 10.0) * pi;
f = sin(x);
}
else
{
if( nfunc == 2 )
{
x = (-0.05 + double(i) / 10.0);
f = exp(x);
}
}
splint(xa, ya, y2, np, x, y);
cout<<setprecision(6)<<setiosflags(ios::fixed);
cout<<setw(12)<<x;
cout<<setw(14)<<f;
cout<<setw(14)<<y<<endl;
}
cout<<"**********************************"<<endl;
}
}
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