Curve by equation

[gb433054]

I am trying to create a curve of a trochoid which has the parametric equation

x = [ a * THETA ] - [ b * sin(THETA) ]
y = a - [ b * cos(THETA) ]

where a & b are real numbers and THETA is the angle in radians.

This is what I used to define the equation in pro, however I dont get the correct shape.

x = ( 0.63662 * ( t * 2000 ) * 0.01745 ) - ( 8.9 * sin ( t * 2000 ) * 0.01745 )
y = 0.63662 - ( 8.9 * cos ( ( t * 2000 ) * 0.01745 ) )
z = 0

Because I require the angle to be in radians I have multiplied the 't' function by Pi/180 which is approx 0.01745

Has anyone any idea what I could be doing wrong

Thanks in advance

 

[Hora]

GB433054,

Please check your math:

sin(theta)*PI/180 IS NOT EQUAL WITH sin(theta*PI/180)

Good luck,

-Hora

 

[gb433054]

good spot, but correct math but still doesnt work :-(

 

[Hora]

Your THETA = 2000 is in radians or degrees?

-Hora

 

[mjcole]

You're going to kick yourself for this later.

You want to convert the angle inside of the parentheses with your angle. That way you will get the sign of the correct angle and not the sign of the angle multiplied by your PI conversion.

Michael