Data commit

Task/Modular-inverse/PL-I/modular-inverse.pli

@@ -0,0 +1,33 @@
+*process source attributes xref or(!);
+ /*--------------------------------------------------------------------
+ * 13.07.2015 Walter Pachl
+ *-------------------------------------------------------------------*/
+ minv: Proc Options(main);
+ Dcl (x,y) Bin Fixed(31);
+ x=42;
+ y=2017;
+ Put Edit('modular inverse of',x,' by ',y,' ---> ',modinv(x,y))
+         (Skip,3(a,f(4)));
+ modinv: Proc(a,b) Returns(Bin Fixed(31));
+ Dcl (a,b,ob,ox,d,t) Bin Fixed(31);
+ ob=b;
+ ox=0;
+ d=1;
+
+ If b=1 Then;
+ Else Do;
+   Do While(a>1);
+     q=a/b;
+     r=mod(a,b);
+     a=b;
+     b=r;
+     t=ox;
+     ox=d-q*ox;
+     d=t;
+     End;
+   End;
+ If d<0 Then
+   d=d+ob;
+ Return(d);
+ End;
+ End;