Add tasks for all the new languages

Task/Combinations-and-permutations/Phix/combinations-and-permutations-1.phix

@@ -0,0 +1,27 @@
+function P(integer n,k)
+    return factorial(n)/factorial(n-k)
+end function
+
+function C(integer n,k)
+    return P(n,k)/factorial(k)
+end function
+
+function lstirling(atom n)
+    if n<10 then
+        return lstirling(n+1)-log(n+1)
+    end if
+    return 0.5*log(2*PI*n) + n*log(n/E + 1/(12*E*n))
+end function
+
+function P_approx(integer n, k)
+    return lstirling(n)-lstirling(n-k)
+end function
+
+function C_approx(integer n, k)
+    return lstirling(n)-lstirling(n-k)-lstirling(k)
+end function
+
+function to_s(atom v)
+integer e = floor(v/log(10))
+    return sprintf("%.9ge%d",{power(E,v-e*log(10)),e})
+end function

Task/Combinations-and-permutations/Phix/combinations-and-permutations-2.phix

@@ -0,0 +1,22 @@
+printf(1,"=> Exact results:\n")
+for n=1 to 12 do
+    integer p = floor(n/3)
+    printf(1,"P(%d,%d) = %d\n",{n,p,P(n,p)})
+end for
+
+for n=10 to 60 by 10 do
+    integer p = floor(n/3)
+    printf(1,"C(%d,%d) = %d\n",{n,p,C(n,p)})
+end for
+
+printf(1,"=> Floating point approximations:\n")
+constant tests = {5, 50, 500, 1000, 5000, 15000}
+for i=1 to length(tests) do
+    integer n=tests[i], p = floor(n/3)
+    printf(1,"P(%d,%d) = %s\n",{n,p,to_s(P_approx(n,p))})
+end for
+
+for n=100 to 1000 by 100 do
+    integer p = floor(n/3)
+    printf(1,"C(%d,%d) = %s\n",{n,p,to_s(C_approx(n,p))})
+end for