SUBROUTINE ERLSIN
C
C     This module of the ERLANG program calculates the probability
C   that a particular number of trunks will be occupied if a given
C   amount of traffic is presented.
C
C      B. Z. Lederman   I.T.T. World Communications
C
      BYTE ANS
C
  220 WRITE (5, 300)
  300 FORMAT ( / '$ Enter Erlangs of traffic, Number of trunks: ')
      READ (5, 310, END=260) A, N
  310 FORMAT (F10.2, I4)
C
      PROBL = EXP(-1. * A)
      IF (N .LE. 0) GO TO 350
      DO 400 I = 1, N
  400 PROBL = PROBL * ( A / FLOAT(I) )
C
  350 WRITE (5, 370) N, A, PROBL
  370 FORMAT ('0 Probability of ', I4, ' trunks occupied with ', F7.2,
     1' Erlangs of traffic = ', F6.2 / 1X /
     2'$ Another Single Trunk problem [Y/N] ?: ')
      READ (5, 420, END=260) ANS
  420 FORMAT (A1)
      IF ((ANS .EQ. 'Y') .OR. (ANS .EQ. 'y')) GO TO 220
C
  260 RETURN
C
      END