' Levenshtein distance
PROGRAM "levenshtein"

DECLARE FUNCTION Entry ()
INTERNAL FUNCTION LevDist(s$, t$)
INTERNAL FUNCTION Min3(a%%, b%%, c%%)

FUNCTION Entry ()
PRINT "The Levenshtein distance..."
PRINT "between 'kitten' and 'sitting' is"; LevDist("kitten", "sitting")
PRINT "between 'rosettacode' and 'raisethysword' is"; LevDist("rosettacode", "raisethysword")
END FUNCTION

FUNCTION LevDist(s$, t$)
n%% = LEN(t$)
m%% = LEN(s$)
DIM d%%[m%%, n%%]
FOR i%% = 0 TO m%%
  d%%[i%%, 0] = i%%
NEXT i%%
FOR j%% = 0 TO n%%
  d%%[0, j%%] = j%%
NEXT j%%
FOR j%% = 1 TO n%%
  FOR i%% = 1 TO m%%
    IF s${i%% - 1} = t${j%% - 1} THEN
      d%%[i%%, j%%] = d%%[i%% - 1, j%% - 1]
    ELSE
      d%%[i%%, j%%] = Min3(d%%[i%% - 1, j%%] + 1, d%%[i%%, j%% - 1] + 1, d%%[i%% - 1, j%% - 1] + 1)
    END IF
  NEXT i%%
NEXT j%%
END FUNCTION d%%[m%%, n%%]

FUNCTION Min3(a%%, b%%, c%%)
tmp%% = a%%
IF b%% < tmp%% THEN tmp%% = b%%
IF c%% < tmp%% THEN tmp%% = c%%
END FUNCTION tmp%%
END PROGRAM