Compute the upper regularized incomplete Gamma function `Q(a, x)`.
  }];

  let description = [{
The upper regularized incomplete Gamma function is defined as:

\\(Q(a, x) = Gamma(a, x) / Gamma(a) = 1 - P(a, x)\\)

where

\\(Gamma(a, x) = \int_{x}^{\infty} t^{a-1} exp(-t) dt\\)

is the upper incomplete Gamma function.

Note, above `P(a, x)` (`Igamma`) is the lower regularized complete

        `tf.math.cos`, `tf.math.cosh`, `tf.math.digamma`, `tf.math.equal`,
        `tf.math.erfc`, `tf.math.exp`, `tf.math.expm1`, `tf.math.floor`,
        `tf.math.greater`, `tf.math.greater_equal`, `tf.math.igamma`,
        `tf.math.igammac`, `tf.math.invert_permutation`, `tf.math.less`,
        `tf.math.less_equal`, `tf.math.lgamma`, `tf.math.log`, `tf.math.log1p`,

213C          ; mapped                 ; 03C0          # 4.1  DOUBLE-STRUCK SMALL PI
213D..213E    ; mapped                 ; 03B3          # 3.2  DOUBLE-STRUCK SMALL GAMMA..DOUBLE-STRUCK CAPITAL GAMMA
213F          ; mapped                 ; 03C0          # 3.2  DOUBLE-STRUCK CAPITAL PI
2140          ; mapped                 ; 2211          # 3.2  DOUBLE-STRUCK N-ARY SUMMATION

		{"Float64frombits", Func, 0},
		{"Floor", Func, 0},
		{"Frexp", Func, 0},
		{"Gamma", Func, 0},
		{"Hypot", Func, 0},
		{"Ilogb", Func, 0},
		{"Inf", Func, 0},
		{"IsInf", Func, 0},
		{"IsNaN", Func, 0},
		{"J0", Func, 0},
		{"J1", Func, 0},
		{"Jn", Func, 0},
		{"Ldexp", Func, 0},
		{"Lgamma", Func, 0},
		{"Ln10", Const, 0},
		{"Ln2", Const, 0},
		{"Log", Func, 0},