gammaIncomplete

Incomplete gamma integral and its complement

These functions are defined by

gammaIncomplete = ( $(INTEGRATE 0, x) e-t ta-1 dt )/ $(GAMMA)(a)

gammaIncompleteCompl(a,x) = 1 - gammaIncomplete(a,x) = ($(INTEGRATE x, ∞) e-t ta-1 dt )/ $(GAMMA)(a)

In this implementation both arguments must be positive. The integral is evaluated by either a power series or continued fraction expansion, depending on the relative values of a and x.

real
gammaIncomplete
(
real a
,
real x
)

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