int main(int argc, char *argv[])
{
using namespace magnet::math;
Spline spline;
//Add points to the spline in any order, they're sorted in ascending
//x later. (If you want to spline a circle you'll need to change the
//class)
spline.addPoint(0, 0.0);
spline.addPoint(40.0/255, 0.0);
spline.addPoint(60.0/255, 0.2);
spline.addPoint(63.0/255, 0.05);
spline.addPoint(80.0/255, 0.0);
spline.addPoint(82.0/255, 0.9);
spline.addPoint(1.0, 1.0);
//spline.addPoint(0, 0);
//spline.addPoint(0.75, 0.5);
//spline.addPoint(1, 1);
//spline.addPoint(0.2, 0.6);
//spline.addPoint(0.5, 0.6);
{ //We can extract the original data points by treating the spline as
//a read-only STL container.
std::ofstream of("orig.dat");
for (Spline::const_iterator iPtr = spline.begin();
iPtr != spline.end(); ++iPtr)
of << iPtr->first << " " << iPtr->second << "\n";
}
{ //A "natural spline" where the second derivatives are set to 0 at the boundaries.
//Each boundary condition is set seperately
//The following aren't needed as its the default setting. The
//zero values are the second derivatives at the spline points.
spline.setLowBC(Spline::FIXED_2ND_DERIV_BC, 0);
spline.setHighBC(Spline::FIXED_2ND_DERIV_BC, 0);
//Note: We can calculate values outside the range spanned by the
//points. The extrapolation is based on the boundary conditions
//used.
std::ofstream of("spline.natural.dat");
for (double x(-0.2); x <= 1.2001; x += 0.005)
of << x << " " << spline(x) << "\n";
}
{ //A spline with a fixed first derivative at the boundaries
//The zero values are the value of the gradient at that point
spline.setLowBC(Spline::FIXED_1ST_DERIV_BC, 0);
spline.setHighBC(Spline::FIXED_1ST_DERIV_BC, 0);
std::ofstream of("spline.fixedy1.dat");
for (double x(-0.2); x <= 1.2001; x += 0.005)
of << x << " " << spline(x) << "\n";
}
{ //A spline which turns into a parabola at the boundaries.
//This BC does not need extra parameters, so just the condition is
//enough.
spline.setLowBC(Spline::PARABOLIC_RUNOUT_BC);
spline.setHighBC(Spline::PARABOLIC_RUNOUT_BC);
std::ofstream of("spline.parabolicrunout.dat");
for (double x(-0.2); x <= 1.2001; x += 0.005)
of << x << " " << spline(x) << "\n";
}
{ //A spline which turns into a parabola at the boundaries.
//This BC does not need extra parameters, so just the condition is
//enough.
spline.setLowBC(Spline::FIXED_1ST_DERIV_BC, 100);
spline.setHighBC(Spline::PARABOLIC_RUNOUT_BC);
std::ofstream of("spline.mixed.dat");
for (double x(-0.2); x <= 1.2001; x += 0.005)
of << x << " " << spline(x) << "\n";
}
// The following class uses splines to interpolate between color
// values to make a "transfer function".
// {
// magnet::color::TransferFunction tf;
// tf.addKnot(0, 0.91, 0.7, 0.61, 0.0);
// tf.addKnot(40.0/255, 0.91, 0.7, 0.61, 0.0);
// tf.addKnot(60.0/255, 0.91, 0.7, 0.61, 0.2);
// tf.addKnot(63.0/255, 0.91, 0.7, 0.61, 0.05);
// tf.addKnot(80.0/255, 0.91, 0.7, 0.61, 0.0);
// tf.addKnot(82.0/255, 1.0, 1.0, 0.85, 0.9);
// tf.addKnot(1.0, 1.0, 1.0, 0.85, 1.0);
//
// //tf.getColorMap();
// }
}
