Created
May 13, 2016 19:07
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void computeCubicSplineCoefficients(double** a, double* x, double* y, int n) | |
{ | |
double** matrix = new double*[n-1]; | |
for (int i=0; i<n-1; i++) | |
matrix[i] = new double[n-1]; | |
double* sol = new double[n-1]; | |
double* rhs = new double[n-1]; | |
/* Füllen Sie hier die Matrix und die rechte Seite mit den entsprechenden Werten. */ | |
for(int i=0;i<n-1;++i) | |
{ | |
double h1 = x[i+1]-x[i]; | |
double h2 = x[i+2]-x[i+1]; | |
if(i-1>=0) | |
matrix[i][i-1]=h1; | |
matrix[i][i]= 2*(h1+h2); | |
if(i+1<n-1) | |
matrix[i][i+1]=h2; | |
rhs[i] = 3*((y[i+2]-y[i+1])/h2-(y[i+1]-y[i])/h1); | |
} | |
a[0][2]=0; | |
a[n-1][2]=0; | |
// solve | |
solveByGaussSeidel(sol, matrix, rhs, n-1); | |
for(int i=0;i<n-1;++i) | |
{ | |
a[i+1][2]=sol[i]; | |
} | |
/* Berechnen Sie hier die Koeffizienten a unter Verwendung der Lösung des LGS. */ | |
for(int i=0;i<n;++i) | |
{ | |
double hi = x[i+1]-x[i]; | |
//a[i][0]=y[i]; | |
a[i][0] = y[i]; | |
if(i>0) | |
{ | |
a[i][3]=(a[i][2]+a[i-1][2])/3*hi; | |
a[i][1]=(y[i]-y[i-1])/hi+a[i][2]-a[i][3]*hi*hi; | |
} | |
else | |
{ | |
a[i][3]=(a[i][2])/3*hi; | |
a[i][1]=(y[i])/hi+a[i][2]-a[i][3]*hi*hi; | |
} | |
std::cout << a[i][3]<<"x^3 + "<< a[i][2]<<"x^2 + "<< a[i][1]<< "x + "<< a[i][0] << std::endl; | |
} | |
//STIMMT | |
// cleanup | |
for (int i=0; i<n-1; i++) | |
delete [] matrix[i]; | |
delete [] matrix; | |
delete [] sol; | |
delete [] rhs; | |
} |
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