Undefined is not iterable (cannot read property Symbol (Symbol.iterator))

[QUAH KAH CHUN UPSI]

h=10

L=40

c1=color.red

r1=1

g=9.81

t=0

dt=0.0001

e=0.7

n=0

c=0

world=canvas(width=600,height=600,center=vec(0,h/2,0),color=color.black)

ground=box(size=vec(L,2,L/4),pos=vec(0,0,0),color=color.blue)

b1=sphere(radius=r1,pos=vec(0,h,0),color=c1)

b1.v,b1.a=vec(0,0,0),vec(0,-g,0)

T=label(text="T="" "+t+" ""s",pos=vec(L/3,2*h,0))

N=label(text="n=5",pos=vec(-L/3,2*h,0))

C=label(text=n,pos=b1.pos,xoffset=30,yoffset=30,visible=False)

def movement(s,v,a,t):

    v+=a*t

    s+=v*t

    return(s,v)

def bounce(sy,r,gy,vy,e,nobounce,c):

    if(sy<=r+gy/2 and vy<0):

        vy=-vy*e

        nobounce+=1

        c.visible=True

        c.text=nobounce

        c.pos=b1.pos

        return(vy,nobounce,c)

while(n<5):

    rate(10000)

    T.text="T="" "+t+" ""s"

    b1.pos,b1.v=movement(b1.pos,b1.v,b1.a,dt)

    b1.v.y,n,C=bounce(b1.pos.y,r1,ground.size.y,b1.v.y,e,n,C)

    t+=dt

I want to define the function "bounce" but it appears this error, how can I fix it?

[Bruce Sherwood]

There are two problems:

1) You need an else in the bounce function. The error you see arises from returning nothing when the if is not executed.

2) You should not return C; the bounce function updates C's visible, text, and pos attributes.

Bruce

[QUAH KAH CHUN UPSI]

GlowScript 3.0 VPython
h=10
L=40
r1,c1=1,color.red
r2,c2=1,color.blue

g=9.81
t=0
dt=0.0001
e=0.7
n=0
c=0

i=0
world=canvas(width=600,height=600,center=vec(0,h/2,0),color=color.black)
ground=box(size=vec(L,2,L/4),pos=vec(0,0,0),color=color.blue)
b1=sphere(radius=r1,pos=vec(0,h,0),color=c1)
b1.v,b1.a=vec(0,0,0),vec(0,-g,0)
b2=sphere(radius=r2,pos=vec(5,2*h,0),color=c2)
b2.v,b2.a=vec(0,0,0),vec(0,-g,0)

T=label(text="T="" "+t+" ""s",pos=vec(L/3,2*h,0))
N=label(text="n=5",pos=vec(-L/3,2*h,0))
C=label(text=n,pos=b1.pos,xoffset=30,yoffset=30,visible=False)

I=label(text=i,pos=b2.pos,xoffset=30,yoffset=30,visible=False)

def movement(s,v,a,t):
    v+=a*t
    s+=v*t
    return(s,v)

def bounce(sy,r,gy,vy,e,nobounce):

    if(sy<=r+gy/2 and vy<0):
        vy=-vy*e
        nobounce+=1

        return(vy,nobounce)
    else:
        nobounce=nobounce
       
while(n<5 or i<5):

    rate(10000)
    T.text="T="" "+t+" ""s"
    b1.pos,b1.v=movement(b1.pos,b1.v,b1.a,dt)

    b2.pos,b2.v=movement(b2.pos,b2.v,b2.a,dt)
    b1.v.y,n=bounce(b1.pos.y,r1,ground.size.y,b1.v.y,e,n)
    b2.v.y,n=bounce(b2.pos.y,r2,ground.size.y,b2.v.y,e,n)
   
    t+=dt

What I have done for the problems:
1) I added else:nobounce=nobounce in the bounce function
2) I have removed the C label from the bounce function temporarily 

However, the error still appears somehow.

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[Harlan Gilbert]

You still need to return something in that "else" tine.

To view this discussion on the web visit https://groups.google.com/d/msgid/glowscript-users/CAALzp4x93gMN_e6EOMsAQQNT%3DmZz%2BMf2hHSBgq-QsJgfbJyy8Q%40mail.gmail.com.

--

Harlan Gilbert

Co-Chair and Math, Physics, Computer Science, and Philosophy Teacher

Green Meadow Waldorf High School

Chestnut Ridge, NY 10977

(845) 356-2514 x. 320

[QUAH KAH CHUN UPSI]

Oh it works, thanks!

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