PV2

c     Main part
      PROGRAM main

      COMMON /const/ rad
      COMMON /input/ Xmin, Xmax, Xstep, Ymin, Ymax, Ystep

      rad = 3.1415927 / 180
      PRINT *, rad

      CALL inputf
      CALL outputf
      END

c     Input values from file
      SUBROUTINE inputf

      COMMON /const/ rad
      COMMON /input/ Xmin, Xmax, Xstep, Ymin, Ymax, Ystep

      OPEN (1, FILE='input.txt', ACTION='READ', STATUS='OLD', ERR=1)
      READ (1, *, ERR=1) Xmin, Xmax, Xstep, Ymin, Ymax, Ystep
      IF (Xmin .GT. Xmax .OR. Ymin .GT. Ymax) GOTO 1
      GOTO 2

    1 PAUSE 'Error: please check the input file'
      STOP
    2 END

c     Write cosec(x+y) result in output file
      SUBROUTINE outputf

      COMMON /const/ rad
      COMMON /input/ Xmin, Xmax, Xstep, Ymin, Ymax, Ystep

      OPEN (2, FILE='output.txt', ACTION='WRITE', ERR=3)

c     Draw the table top
      WRITE (2, 13) '|   y\x    '
      ri = Xmin
      DO WHILE (ri .LT. Xmax)
         WRITE (2, 10) ri * rad
         ri = ri + Xstep
      END DO
      WRITE (2, 10) Xmax
      WRITE (2, 13) '|'
      WRITE (2, 14)

c     Peredelat'

      IF(MOD((Xmax - Xmin),Xstep).EQ.0)THEN
        iparts = (Xmax - Xmin) / Xstep + 1
      ELSE
        iparts = (Xmax - Xmin) / Xstep + 2
      ENDIF

c     Peredelat'

      DO i = 0, iparts, 1
        WRITE (2, 12)
      END DO
      WRITE (2, 13) '|'
      WRITE (2, 14)


      ry = Ymin
      DO WHILE(ry.LT.Ymax)
        rx = Xmin
        WRITE(2, 10) ry * rad
        DO WHILE(rx.LT.Xmax)
            IF(SIN(rx + ry).EQ.0) WRITE(2, 15) 'NaN'
            IF(SIN(rx+ry).NE.0) WRITE(2, 10) 1 / SIN((rx + ry) * rad)
            rx = rx + Xstep
        END DO
        WRITE(2, 10) 1 / SIN((rx + Ymax) * rad)
        WRITE(2, 13) '|'
        WRITE (2, 14)
        ry = ry + Ystep
        DO i = 0, iparts, 1
            WRITE (2, 12)
        END DO
        WRITE (2, 13) '|'
        WRITE (2, 14)
      END DO

      WRITE(2, 10) Ymax
      rx = Xmin
        DO WHILE(rx.LT.Xmax)
            WRITE(2, 10) 1 / SIN((rx + Ymax) * rad)
            rx = rx + Xstep
        END DO
      WRITE(2, 10) 1 / SIN((Xmax + Ymax) * rad)
      WRITE(2, 13) '|'
      WRITE (2, 14)

      GOTO 4
    3 PAUSE 'Error: please check the output file'
      STOP

   10 FORMAT ('|'E9.4' '\)
   11 FORMAT ('|'F11.4' '\)
   12 FORMAT ('|'10('—')\)
   13 FORMAT (a\)
   14 FORMAT (/1x\)
   15 FORMAT ('|'A9' '\)

    4 END