I just notice ResourceFunction["InterpolatingFunctionToPiecewise"] is broken in v13.1. (Perhaps it's in v13.0, I'm not sure. ) Here's a sample:
f = Interpolation[{1, 2, 3, 5, 8, 5}];
pw[x_] = ResourceFunction["InterpolatingFunctionToPiecewise"][f, x]
LinearAlgebra`Private`VandermondeSolve::optx: Unknown optionTransposeinLinearAlgebra`Private`VandermondeSolve[{0,1/3,2/3,1},{1,113/81,139/81,2},Transpose->True].……
The reason is clear: InterpolatingFunctionToPiecewise has called an undocumented function VandermondeSolve and it no longer owns the option Transpose in v13.1. But how to fix?
interpolationToPiecewise[f, x]works... – Michael E2 Aug 07 '22 at 02:49