Solved #64 by replacing the bracketing interval $[0, \pi/2]$ in groove geometry solving by $[\epsilon, \pi/2-\epsilon]$ with $\epsilon=10^{-6}$. The value was tried out to effectively prevent the trigonometric function from getting 0 or 1, and so preventing division by zero in the numeric solvers.
Solved #64 by replacing the bracketing interval $[0, \pi/2]$ in groove geometry solving by $[\epsilon, \pi/2-\epsilon]$ with $\epsilon=10^{-6}$. The value was tried out to effectively prevent the trigonometric function from getting 0 or 1, and so preventing division by zero in the numeric solvers.