10 CLS
20 DEF FN MR(S) = B1 + (S - A1) * (B2 - B1) / (A2 - A1)
30 A1 = 0: A2 = 10: B1 = -1: B2 = 0
40 FOR X = A1 TO A2
50  PRINT X; "maps to "; FN MR(X)
60 NEXT X
70 END