Data update

Task/Gamma-function/VBA/gamma-function.vba

@@ -0,0 +1,35 @@
+' Gamma function
+
+Sub MainGamma()
+  Dim X As Double
+  For X = 0.1 To 2.05 Step 0.1
+    Debug.Print X, FNGamma(X)
+  Next X
+End Sub
+
+Function FNGamma(Z As Double) As Double
+  FNGamma = Exp(FNLnGamma(Z))
+End Function
+
+Function FNLnGamma(ByVal Z As Double) As Double
+  Dim LZ(6) As Double
+  LZ(0) = 1.00000000019001
+  LZ(1) = 76.1800917294715
+  LZ(2) = -86.5053203294168
+  LZ(3) = 24.0140982408309
+  LZ(4) = -1.23173957245015
+  LZ(5) = 1.2086509738662E-03
+  LZ(6) = -0.000005395239385
+  Pi = WorksheetFunction.Pi()
+  If Z < 0.5 Then
+    FNLnGamma = Log(Pi / Sin(Pi * Z)) - FNLnGamma(1# - Z)
+  Else
+    Z = Z - 1#
+    B = Z + 5.5
+    A = LZ(0)
+    For I = 1 To 6
+      A = A + LZ(I) / (Z + I)
+    Next I
+    FNLnGamma = (Log(Sqr(2 * Pi)) + Log(A) - B) + Log(B) * (Z + 0.5)
+  End If
+End Function