INCLUDE "D2:REAL.ACT" ;from the Action! Tool Kit

PROC Map(REAL POINTER a1,a2,b1,b2,s,res)
  REAL tmp1,tmp2,tmp3

  RealSub(s,a1,tmp1) ;tmp1=s-a1
  RealSub(b2,b1,tmp2) ;tmp2=b2-b1
  RealMult(tmp1,tmp2,tmp3) ;tmp3=(s-a1)*(b2-b1)
  RealSub(a2,a1,tmp1) ;tmp1=a2-a1
  RealDiv(tmp3,tmp1,tmp2) ;tmp2=(s-a1)*(b2-b1)/(a2-a1)
  RealAdd(b1,tmp2,res) ;res=b1+(s-a1)*(b2-b1)/(a2-a1)
RETURN

PROC Main()
  BYTE i
  REAL a1,a2,b1,b2,s,res

  Put(125) PutE() ;clear screen

  ValR("0",a1) ValR("10",a2)
  ValR("-1",b1) ValR("0",b2)

  FOR i=0 TO 10
  DO
    IntToReal(i,s)
    Map(a1,a2,b1,b2,s,res)
    PrintR(s) Print(" maps to ")
    PrintRE(res)
  OD
RETURN