September 2017 Update

Task/Matrix-exponentiation-operator/Phix/matrix-exponentiation-operator.phix

@@ -0,0 +1,55 @@
+function identity(integer n)
+sequence res = repeat(repeat(0,n),n)
+    for i=1 to n do
+        res[i][i] = 1
+    end for
+    return res
+end function
+
+function matrix_mul(sequence a, sequence b)
+sequence c
+    if length(a[1]) != length(b) then
+        return 0
+    else
+        c = repeat(repeat(0,length(b[1])),length(a))
+        for i=1 to length(a) do
+            for j=1 to length(b[1]) do
+                for k=1 to length(a[1]) do
+                    c[i][j] += a[i][k]*b[k][j]
+                end for
+            end for
+        end for
+        return c
+    end if
+end function
+
+function matrix_exponent(sequence m, integer n)
+integer l = length(m)
+    if n=0 then return identity(l) end if
+    sequence res = m
+    for i=2 to n do
+        res = matrix_mul(res,m)
+    end for
+    return res
+end function
+
+constant M1 = {{5}}
+constant M2 = {{3, 2},
+               {2, 1}}
+constant M3 = {{1, 2, 0},
+               {0, 3, 1},
+               {1, 0, 0}}
+
+ppOpt({pp_Nest,1})
+pp(matrix_exponent(M1,0))
+pp(matrix_exponent(M1,1))
+pp(matrix_exponent(M1,2))
+puts(1,"==\n")
+pp(matrix_exponent(M2,0))
+pp(matrix_exponent(M2,1))
+pp(matrix_exponent(M2,2))
+pp(matrix_exponent(M2,10))
+puts(1,"==\n")
+pp(matrix_exponent(M3,10))
+puts(1,"==\n")
+pp(matrix_exponent(identity(4),5))