Data commit

Task/Gamma-function/V-(Vlang)/gamma-function.v

@@ -0,0 +1,21 @@
+import math
+fn main() {
+    println("    x               math.Gamma                 Lanczos7")
+    for x in [-.5, .1, .5, 1, 1.5, 2, 3, 10, 140, 170] {
+        println("${x:5.1f} ${math.gamma(x):24.16} ${lanczos7(x):24.16}")
+    }
+}
+
+fn lanczos7(z f64) f64 {
+    t := z + 6.5
+    x := .99999999999980993 +
+        676.5203681218851/z -
+        1259.1392167224028/(z+1) +
+        771.32342877765313/(z+2) -
+        176.61502916214059/(z+3) +
+        12.507343278686905/(z+4) -
+        .13857109526572012/(z+5) +
+        9.9843695780195716e-6/(z+6) +
+        1.5056327351493116e-7/(z+7)
+    return math.sqrt2 * math.sqrt_pi * math.pow(t, z-.5) * math.exp(-t) * x
+}