C Created:  Joe Zachary, October 26, 1992
C Modified:

C This function takes a real number "X" as an argument and computes
C its square root using an approximation algorithm.

      REAL FUNCTION SROOT (X, COUNT)

      IMPLICIT NONE
      REAL X, GUESS
      INTEGER COUNT, I

      GUESS = 1
      DO I = 1, COUNT
         GUESS = (GUESS + X/GUESS) / 2
      ENDDO

      SROOT = GUESS
      RETURN
      END


C This program tests out the SROOT function.  It also prints out
C the result of the intrinsic SQRT function for comparison.

      PROGRAM SRTEST

      IMPLICIT NONE
      REAL Y, SROOT
      INTEGER N

      PRINT *, 'Enter a real number'
      READ *, Y

      PRINT *, 'Enter an integer'
      READ *, N

      PRINT *, 'The approximate square root of ',
     +         Y, ' is ', SROOT(Y, N)

      PRINT *, 'Fortran''s approximation is ', SQRT(Y)

      STOP
      END