# -*- tcl -*- tcl.tk//DSL diagram//EN//1.0

set boxwidth [25 mm]
set boxheight [1 cm]
set movelength [5 mm]

proc result {n} {
    box fillcolor grey text "R($n)"
}
proc iter {n} {
    box text "I($n)"
}
proc output {n} {
    group { south ; arrow ; result $n }
}
proc stepfun {} {
    block {
	east ; set W [line] ; line ; line ; ellipse "\u21932" width [1 cm] ; line ; set E [line]

	south ; line from [$E start] ; line ; line

	west ; arrow
	ellipse "\u21912" width [1 cm]
	arrow
	ellipse text "\u2296" width [1 cm] ;#color ""
	group {
	    north
	    arrow <-
	    line
	    circle radius 2 with center fillcolor black
	}
	group { south ; set S [line] }

	circle radius 2 at [$E start] with center fillcolor black

	set west  [$W start]
	set east  [$E end]
	set south [$S end]
    }
}

box "image" ; output 0
arrow
stepfun ; output 1
arrow
iter 1
move
text text ...
move
iter steps-1
arrow
stepfun ; output steps
arrow
iter steps ; output steps+1