using math inside exp()

[coseng]

hi, i am trying to create a logarithmic spiral using an equation driven datum curve. the general equation is r=a*exp(theta)

in 'datum curve driven by equation', the equation is parametrized by t from 0 to 1, so for one full spiral the equations in the text editor become:

theta=t*360
r=a*exp(t*360)
z=0

this is easy, except for the fact that pro does not seem to let you have mathematical expressions in the exp() function. whenever i type this in in get an error. if i leave out the '*360' in the r equation it works but the scaling is not what i need. i've tried defining variables equal to t*360 and using that in the exp() function, tried other formatting, but nothing with a math expression seems to work. is this true? are there any workarounds?

Thanks,

chris

 

[dr_gallup]

It allows multiplication. Try replacing 360 with 2, it works. Do you know how big e^360 is? It overflows the stack on my calculator & I expect Pro/E too.

 

[coseng]

aaah, i feel silly. windows calc.exe has no problem! seems so easy at

http://mathworld.wolfram.com/LogarithmicSpiral.html

thanks, i guess the coefficients need to be tweaked to get the proper curvature.



chris

 

[gkbeer]

aaah, i feel silly. windows calc.exe has no problem! seems so easy at

http://mathworld.wolfram.com/LogarithmicSpiral.html

thanks, i guess the coefficients need to be tweaked to get the proper curvature.



chris

theta = t * 360 * 5
r=5*t*exp(5*t)
z=0

Edited by: gkbeer