Solve function giving [ ] result
05-06-2014, 01:07 AM
Post: #1
 Rich Junior Member Posts: 47 Joined: Jan 2014
Solve function giving [ ] result
Hello,

When trying to solve this equation i get a result of [], anyone else getting a similar result or perhaps can see an error in my method?

Trying to solve for x here:
348.4=269.65+.5*(315-269.65)+((x/26000)^2 + .25*(315-269.65)^2)^.5

I use the solve function:

solve('348.4=269.65+.5*(315-269.65)+((x/26000)^2 + .25*(315-269.65)^2)^.5', x)

and i get this result:
[]

Thanks
05-06-2014, 06:52 AM
Post: #2
 parisse Senior Member Posts: 1,236 Joined: Dec 2013
RE: Solve function giving [ ] result
If you run solve on an equation with approx data, then fsolve is called instead. Since no interval or guess is provided, the solver tries bisection in tan(-1.57)..tan(1.57), but unfortunately the solutions are outside. You can either give a bisection interval and call fsolve, or run solve(exact(your_equation))
05-06-2014, 12:12 PM (This post was last modified: 05-06-2014 12:17 PM by Rich.)
Post: #3
 Rich Junior Member Posts: 47 Joined: Jan 2014
RE: Solve function giving [ ] result
Using fsolve with an estimated starting point worked.

Thanks!
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