int main(void)
{
int i,j;
float d1,d2,ee,x1x2;
float y[5],y1[5],y2[5],y12[5],**c;
static float x1[]={0.0,0.0,2.0,2.0,0.0};
static float x2[]={0.0,0.0,0.0,2.0,2.0};
c=matrix(1,4,1,4);
d1=x1[2]-x1[1];
d2=x2[4]-x2[1];
for (i=1;i<=4;i++) {
x1x2=x1[i]*x2[i];
ee=exp(-x1x2);
y[i]=x1x2*ee;
y1[i]=x2[i]*(1.0-x1x2)*ee;
y2[i]=x1[i]*(1.0-x1x2)*ee;
y12[i]=(1.0-3.0*x1x2+x1x2*x1x2)*ee;
}
bcucof(y,y1,y2,y12,d1,d2,c);
printf("\nCoefficients for bicubic interpolation:\n\n");
for (i=1;i<=4;i++) {
for (j=1;j<=4;j++) printf("%12.6f",c[i][j]);
printf("\n");
}
free_matrix(c,1,4,1,4);
return 0;
}
void bcuint(float y[], float y1[], float y2[], float y12[], float x1l,
float x1u, float x2l, float x2u, float x1, float x2, float *ansy,
float *ansy1, float *ansy2)
{
void bcucof(float y[], float y1[], float y2[], float y12[], float d1,
float d2, float **c);
int i;
float t,u,d1,d2,**c;
c=matrix(1,4,1,4);
d1=x1u-x1l;
d2=x2u-x2l;
bcucof(y,y1,y2,y12,d1,d2,c);
if (x1u == x1l || x2u == x2l) nrerror("Bad input in routine bcuint");
t=(x1-x1l)/d1;
u=(x2-x2l)/d2;
*ansy=(*ansy2)=(*ansy1)=0.0;
for (i=4;i>=1;i--) {
*ansy=t*(*ansy)+((c[i][4]*u+c[i][3])*u+c[i][2])*u+c[i][1];
*ansy2=t*(*ansy2)+(3.0*c[i][4]*u+2.0*c[i][3])*u+c[i][2];
*ansy1=u*(*ansy1)+(3.0*c[4][i]*t+2.0*c[3][i])*t+c[2][i];
}
*ansy1 /= d1;
*ansy2 /= d2;
free_matrix(c,1,4,1,4);
}
void NR::bcuint(Vec_I_DP &y, Vec_I_DP &y1, Vec_I_DP &y2, Vec_I_DP &y12,
const DP x1l, const DP x1u, const DP x2l, const DP x2u,
const DP x1, const DP x2, DP &ansy, DP &ansy1, DP &ansy2)
{
int i;
DP t,u,d1,d2;
Mat_DP c(4,4);
d1=x1u-x1l;
d2=x2u-x2l;
bcucof(y,y1,y2,y12,d1,d2,c);
if (x1u == x1l || x2u == x2l)
nrerror("Bad input in routine bcuint");
t=(x1-x1l)/d1;
u=(x2-x2l)/d2;
ansy=ansy2=ansy1=0.0;
for (i=3;i>=0;i--) {
ansy=t*ansy+((c[i][3]*u+c[i][2])*u+c[i][1])*u+c[i][0];
ansy2=t*ansy2+(3.0*c[i][3]*u+2.0*c[i][2])*u+c[i][1];
ansy1=u*ansy1+(3.0*c[3][i]*t+2.0*c[2][i])*t+c[1][i];
}
ansy1 /= d1;
ansy2 /= d2;
}
void bcuint(double y[], double y1[], double y2[], double y12[], double x1l,
double x1u, double x2l, double x2u, double x1, double x2, double *ansy,
double *ansy1, double *ansy2, double *c)
{
//y--;y1--;y2--;y12--;
int i;
double t,u,d1,d2;
d1=x1u-x1l;
d2=x2u-x2l;
bcucof(y,y1,y2,y12,d1,d2,c);
//if (x1u == x1l || x2u == x2l)
// nrerror("Bad input in routine bcuint");
t=(x1-x1l)/d1;
u=(x2-x2l)/d2;
*ansy=(*ansy2)=(*ansy1)=0.0;
for (i=3;i>=0;i--)
{
*ansy=t*(*ansy)+((c[i*4+3]*u+c[i*4+2])*u+c[i*4+1])*u+c[i*4+0];
*ansy2=t*(*ansy2)+(3.0*c[i*4+3]*u+2.0*c[i*4+2])*u+c[i*4+1];
*ansy1=u*(*ansy1)+(3.0*c[3*4+i]*t+2.0*c[2*4+i])*t+c[1*4+i];
}
*ansy1 /= d1;
*ansy2 /= d2;
}
