This example shows the use of the SPLINE statement in constructing boundary curves.
A circular arc is approximated by five spline segments.
The end segments are made very short to establish the proper slope at the ends.
The problem solves a heatflow equation on a quarter circle and compares the solution
with the analytic value.
title 'Spline Boundary'
k = 1
u0 = 1-r^2
s = 4
U: div(k*grad(u)) + s = 0
natural(u) = 0 line to (1,0)
spline to(0.99985,0.01745) ! short initial interval to establish slope
to (0.01745,0.99985) ! short final interval to establish slope
natural(u)=0 line to close