Ask Your Question

Solving equations for the parmaters

asked 2017-04-06 20:39:11 -0500

$$ xe^{-1/y}=0.6$$ and $$xye^{-1}=1.2$$

I am trying to solve this equations for approximate value of the parameters $x$ and $y$ using SageMath. any help would be appreciated.

edit retag flag offensive close merge delete


What did you try?

vdelecroix gravatar imagevdelecroix ( 2017-04-07 02:06:47 -0500 )edit

1 answer

Sort by ยป oldest newest most voted

answered 2017-04-07 12:20:35 -0500

dan_fulea gravatar image

updated 2017-04-07 12:21:29 -0500

The two equations allow a quick elimination of $x>0$. We can than numerically solve the remaining one equation in the remaining single variable $y$. The following code may help to get the relevant information, adapted to my taste:

sage: f(y) = log(y) +1/y -1 - log(2)
sage: f
y |--> 1/y - log(2) + log(y) - 1
sage: plot( f, 0.2, 0.5 )
Launched png viewer for Graphics object consisting of 1 graphics primitive
sage: find_root( f, 0.2, 0.4 )
sage: gp( "solve( y=0.2, 0.4, %s )" %f(y) )

(The value for $x$ is easily found from the second equation.)

edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools

1 follower


Asked: 2017-04-06 20:39:11 -0500

Seen: 79 times

Last updated: Apr 07