Time constant of an LRC circuit

eljaydub

I'm having trouble finding an equation for the time constant of an LRC circuit as a function of L, R and C. (In the same way that RC is time constant for an RC circuit) Does anyone know what the equation is?
Thanks!

eljaydub

Hmm maybe I'll not representing this right...
Say I have an equation of the form
A*exp(-a*x)*cos(b*x+c)
for an LCR where A,a,b,c are parameters. Then 'a' corresonds to 1/(TimeConstant) but there should be a formula similar to 1/RC for an RC circuit to predict the value of that constant.
I'm looking for the formula so that I can justify my guess of the parameter to fit it to my experimental data

eljaydub

*bump*
No help?