C
C PAGE 63-65: NUMERICAL MATHEMATICS AND COMPUTING, CHENEY/KINCAID, 1985
C
C FILE: XSINX.FOR
C
C EXAMPLE OF PROGRAMMING F(X) = X - SIN(X) CAREFULLY (F)
C
      DOUBLE PRECISION DX,DY,DZ       
      DX = 1.0D0/15.0D0     
      DY = DSIN(DX) 
      DZ = DX - DY
      PRINT *,DX,DY,DZ      
      X = 16.0    
      DO 2 N = 1,52 
        X = 0.25*X
        Y = F(X)  
        PRINT *,N,X,Y       
   2  CONTINUE
      X = SIN(1.0)
      Y = F(1.0)
      PRINT *,X,Y 
      STOP
      END 
  
      FUNCTION F(X) 
      IF(ABS(X) .GE. 1.9) THEN
        F = X - SIN(X)
      ELSE
        T = X**3/6.0
        F = T     
        DO 2 N = 1,9
          T = -T*X*X/REAL((2*N+2)*(2*N+3))      
          F = F + T 
   2    CONTINUE  
      END IF      
      RETURN
      END