Data commit

Task/Animate-a-pendulum/ERRE/animate-a-pendulum.erre

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+PROGRAM PENDULUM
+
+!
+! for rosettacode.org
+!
+
+!$KEY
+
+!$INCLUDE="PC.LIB"
+
+PROCEDURE PENDULUM(A,L)
+      PIVOTX=320
+      PIVOTY=0
+      BOBX=PIVOTX+L*500*SIN(a)
+      BOBY=PIVOTY+L*500*COS(a)
+      LINE(PIVOTX,PIVOTY,BOBX,BOBY,6,FALSE)
+      CIRCLE(BOBX+24*SIN(A),BOBY+24*COS(A),27,11)
+      PAUSE(0.01)
+      LINE(PIVOTX,PIVOTY,BOBX,BOBY,0,FALSE)
+      CIRCLE(BOBX+24*SIN(A),BOBY+24*COS(A),27,0)
+END PROCEDURE
+
+BEGIN
+      SCREEN(9)
+      THETA=40*p/180     ! initial displacement
+      G=9.81             ! acceleration due to gravity
+      L=0.5              ! length of pendulum in metres
+      LINE(0,0,639,0,5,FALSE)
+      LOOP
+        PENDULUM(THETA,L)
+        ACCEL=-G*SIN(THETA)/L/100
+        SPEED=SPEED+ACCEL/100
+        THETA=THETA+SPEED
+      END LOOP
+END PROGRAM