message: Correct a mistake in the lgamma documentation
  The lower regularized incomplete Gamma function as defined in the documentation is P(a, x) but the heading for the function is Q(a, x). This is incorrect, Q(a, x) refers to the upper regularized incomplete Gamma function.
diff: op {
  graph_op_name: "Igamma"
  - summary: "Compute the lower regularized incomplete Gamma function `Q(a, x)`."
  + summary: "Compute the lower regularized incomplete Gamma function `P(a, x)`."
  description: <<END
  The lower regularized incomplete Gamma function is defined as:
  