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 '
WRITE (2, 11) Xmin
ri = Xmin + Xstep
DO WHILE (ri .LT. Xmax)
WRITE (2, 11) ri
ri = ri + Xstep
END DO
WRITE (2, 11) Xmax
WRITE (2, 13) '|'
WRITE (2, 14)

c I cant round iparts up, so... +2 instead of +1
iparts = (Xmax - Xmin) / Xstep + 2
DO i = 0, iparts, 1
WRITE (2, 12)
END DO
WRITE (2, 13) '|'

c Do something blablabla fix it
c I HATE FORTRAN


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

10 FORMAT ('|'E11.4' '\)
11 FORMAT ('|'F11.4' '\)
12 FORMAT ('|'12('—')\)
13 FORMAT (a\)
14 FORMAT (/1x\)

4 END