REBOL [ File: %pytagoras-thorem.r Date: 25-9-2014 Title: "Pytagoras' theorem" Purpose: { User friendly interface to apply the Pytagoras' theorem. } Author: "Caridorc" library: [ level: 'beginner platform: 'all type: [tool] domain: [Math] tested-under: "Windows" support: riki100024 AT gmail DOT com license: CC 3.0 Attribution only see-also: none ] ] view layout [ box white 550x300 effect [ draw [ line-width 4 pen blue line 80x210 520x210 ; C pen red line 80x210 80x50 ; c pen green line 80x50 520x210 ; i ] ] below across text "c" red font-size 25 a: field font-size 25 200x35 below across text "C" blue font-size 25 b: field font-size 25 200x35 below across text "i" leaf font-size 25 c: field font-size 25 200x35 below button "Calculate" font-size 25 130x35 [ if (a/text = "") [alert join "c = " to-string (square-root (((power (to-integer c/text) 2) - (power (to-integer b/text) 2))))] if (b/text = "") [alert join "C = " to-string (square-root (((power (to-integer c/text) 2) - (power (to-integer a/text) 2))))] if (c/text = "") [alert join "i = " to-string (square-root (((power (to-integer a/text) 2) + (power (to-integer b/text) 2))))] if (all [a/text <> "" b/text <> "" c/text <> ""]) [alert "Leave at least one blank"] ] ]