I am running a script using a reparameterisation trick on the Dirichlet distribution sampling from a gamma distribution I am using the torch.igammac(x,0) function. I am getting this error message:
Exception has occurred: RuntimeError       (note: full exception trace is shown but execution is paused at: _run_module_as_main)
the derivative for 'igammac: input' is not implemented.

Getting the derivative of the gamma function shouldnt be so difficult. so why is it not implemented? Is it easy to just add it myself?