Initial data commit

Task/Feigenbaum-constant-calculation/Fortran/feigenbaum-constant-calculation.f

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+      program feigenbaum
+      implicit none
+
+      integer i, j, k
+      real ( KIND = 16 ) x, y, a, b, a1, a2, d1
+
+      print '(a4,a13)', 'i', 'd'
+
+      a1 = 1.0;
+      a2 = 0.0;
+      d1 = 3.2;
+
+      do i=2,20
+         a = a1 + (a1 - a2) / d1;
+         do j=1,10
+            x = 0
+            y = 0
+            do k=1,2**i
+                y = 1 - 2 * y * x;
+                x = a - x**2;
+            end do
+            a = a - x / y;
+         end do
+
+         d1 = (a1 - a2) / (a - a1);
+         a2 = a1;
+         a1 = a;
+         print '(i4,f13.10)', i, d1
+     end do
+     end