DOUBLE PRECISION FUNCTION DMACH(JOB)
      INTEGER JOB
C
C     SMACH COMPUTES MACHINE PARAMETERS OF FLOATING POINT
C     ARITHMETIC FOR USE IN TESTING ONLY.  NOT REQUIRED BY
C     LINPACK PROPER.
C
C     IF TROUBLE WITH AUTOMATIC COMPUTATION OF THESE QUANTITIES,
C     THEY CAN BE SET BY DIRECT ASSIGNMENT STATEMENTS.
C     ASSUME THE COMPUTER HAS
C
C        B = BASE OF ARITHMETIC
C        T = NUMBER OF BASE  B  DIGITS
C        L = SMALLEST POSSIBLE EXPONENT
C        U = LARGEST POSSIBLE EXPONENT
C
C     THEN
C
C        EPS = B**(1-T)
C        TINY = 100.0*B**(-L+T)
C        HUGE = 0.01*B**(U-T)
C
C     DMACH SAME AS SMACH EXCEPT T, L, U APPLY TO
C     DOUBLE PRECISION.
C
C     CMACH SAME AS SMACH EXCEPT IF COMPLEX DIVISION
C     IS DONE BY
C
C        1/(X+I*Y) = (X-I*Y)/(X**2+Y**2)
C
C     THEN
C
C        TINY = SQRT(TINY)
C        HUGE = SQRT(HUGE)
C
C
C     JOB IS 1, 2 OR 3 FOR EPSILON, TINY AND HUGE, RESPECTIVELY.
C
      DOUBLE PRECISION EPS,TINY,HUGE,S
C
      EPS = 1.0D0
   10 EPS = EPS/2.0D0
      S = 1.0D0 + EPS
      IF (S .GT. 1.0D0) GO TO 10
      EPS = 2.0D0*EPS
C
      S = 1.0D0
   20 TINY = S
      S = S/16.0D0
      IF (S*1.0 .NE. 0.0D0) GO TO 20
      TINY = (TINY/EPS)*100.0
      HUGE = 1.0D0/TINY
C
      IF (JOB .EQ. 1) DMACH = EPS
      IF (JOB .EQ. 2) DMACH = TINY
      IF (JOB .EQ. 3) DMACH = HUGE
      RETURN
      END