Initial data commit

Task/Modular-inverse/Forth/modular-inverse-1.fth

@@ -0,0 +1,10 @@
+: invmod { a m | v b c -- inv }
+  m to v
+  1 to c
+  0 to b
+  begin a
+  while v a / >r
+     c b s>d c s>d r@ 1 m*/ d- d>s to c to b
+     a v s>d a s>d r> 1 m*/ d- d>s to a to v
+  repeat b m mod dup to b 0<
+  if m b + else b then ;

Task/Modular-inverse/Forth/modular-inverse-2.fth

@@ -0,0 +1,18 @@
+: modinv ( a m - inv)
+  dup 1-              \ a m (m != 1)?
+  if                  \ a m
+    tuck 1 0          \ m0 a m 1 0
+    begin             \ m0 a m inv x0
+      2>r over 1 >    \ m0 a m (a > 1)?       R: inv x0
+    while             \ m0 a m                R: inv x0
+      tuck /mod       \ m0 m (a mod m) (a/m)  R: inv x0
+      r> tuck *       \ m0 a' m' x0 (a/m)*x0  R: inv
+      r> swap -       \ m0 a' m' x0 (inv-q)   R:
+    repeat            \ m0 a' m' inv' x0'
+    2drop             \ m0                    R: inv x0
+    2r> drop          \ m0 inv                R:
+    dup 0<            \ m0 inv (inv < 0)?
+    if over + then    \ m0 (inv + m0)
+  then                \ x inv'
+  nip                 \ inv
+;