Hard hyperbolic tan integral :/

[khfrekek92]

Homework Statement

tanh{[(2 *g*t)/(c)]+[(2*g*exp(-rt))/(r*c)]-[(2*)/(r*c)]} in terms of t

Homework Equations

when I plug into maple I get -(1/4)*c*ln(tanh(2*g*(t+1/r(e^(-rt))-1/r)/c)-1)/g-(1/4)*c*ln(tanh(2*g*(t+1/r(e^(-rt))-1/r)/c)+1)/g

The Attempt at a Solution

This cannot be right.. I always thought the integral of tanh was log(cosh)? Plus when I enter all the constants and evaluate at the bounds (g=9.8, r=1/94670777.9, t=3.156*10^8, c=3*10^8) I get an answer of [(ln(0)+ln(2))-(ln(-1)+ln1)] Which is an impossible answer, even if I omit the undefined ones, I still get an answer that should not be related to relativity..

Any help would be greatly appreciated! Thank you so much!

 

[khfrekek92]

Here is the maple file I used

 

[khfrekek92]

is this integral even integrateable?

 

[Hurkyl]

Something looks wrong with what you've written: see

http://www.wolframalpha.com/input/?...1/r(Exp[-rt])-1/r)/c]+1]/g,t]&incParTime=true


*insert lecture on symbolic manipulation, branch cuts, indefinite, define, and improper integrals*


In the end, it's probably simpler to ask maple to compute a definite integral instead of an indefinite integral -- and maybe even to substitute in the known constants before integrating.