'===========================================================================
' Subject: SIMPLE HARMONIC MOTION            Date: 04-18-99 (21:56)       
' Author:  Ross Harper                       Code: QB, QBasic, PDS        
' Origin:  t.r.harper@btinternet.com       Packet: GRAPHICS.ABC
'===========================================================================
'' Howdy!
'' Just a little program that I threw together one Sunday, in the hope of
'' illustrating Simple Harmonic Motion for my A-Level Physics.
''
'' As you can probably guess, I need more revision...
''
'' Not much of a program mind you, but let me know what you think.
''
'' Ross
'' Peachy512@yahoo.com
'' ICQ: 15844814
'' The Zax Bypass: http://members.xoom.com/Peachy512/Asylum/home.htm

DECLARE SUB pause (s!)
SCREEN 9
''INPUT "Amplitude.."; A
''INPUT "Pulsitance.."; w
pi = 3.141592654#
a = 50
f = 10
w = 2 * pi * f

''draw grid!
LINE (0, 200 - a)-(0, 200 + a), 14
LINE (0, 200)-(640, 200), 14

x1 = 0: y1 = 200
FOR t = 5 TO 640 STEP 1
        w = INT(2 * pi * f)
        y = 200 + (a * SIN(w * t))
        LINE (x1, y1)-(t, y)
        y1 = y: x1 = t
        pause (1)
        a$ = LCASE$(INKEY$)
        IF a$ = "q" THEN w = w + 5
        IF a$ = "a" THEN w = w - 5
       
        IF a$ = "e" THEN f = f + 5
        IF a$ = "d" THEN f = f - 5
       
        IF a$ = "w" THEN a = a + 5
        IF a$ = "s" THEN a = a - 5
        LOCATE 1, 1: PRINT "A="; a
        LOCATE 2, 1: PRINT "w="; w
        LOCATE 3, 1: PRINT "f="; f
NEXT t

SUB pause (s)
FOR zog = 1 TO s
        starttime = TIMER
        DO
        LOOP UNTIL TIMER <> starttime
NEXT zog
END SUB