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From: El Hassan Abdel Fattah on 19 Mar 2010 17:51
Hello all,

I'm trying to solve a mechanics of materials equation for buckling using matlab, but I do not know how to solve an equation for a specific variable. My equation is :
0.6 = 0.5(sec(sqrt(P/EI)*60) -1)

where EI is defined and P is the unkown I'm solving for. Any help will be greatly appreciated. Thanks in advance!

Hassan
From: Nathan on 19 Mar 2010 17:58
On Mar 19, 2:51 pm, "El Hassan Abdel Fattah" <s8...(a)unb.ca> wrote:
> Hello all,
>
> I'm trying to solve a mechanics of materials equation for buckling using matlab, but I do not know how to solve an equation for a specific variable. My equation is :
> 0.6 = 0.5(sec(sqrt(P/EI)*60) -1)
>
> where EI is defined and P is the unkown I'm solving for. Any help will be greatly appreciated. Thanks in advance!
>
> Hassan

You don't know how to do this mathematically?

..6 = .5(sec(sqrt(P/EI)*60)-1)
%divide both sides by .5
1.2 = sec(sqrt(P/EI)*60)-1
%add 1 to both sides
2.2 = sec(sqrt(P/EI)*60)
%apply inverse secant to both sides
asec(2.2) = sqrt(P/EI)*60
%divide both sides by 60
asec(2.2)/60 = sqrt(P/EI)
%square both sides
(asec(2.2)/60)^2 = P/EI
%multiply both sides by EI
EI*(asec(2.2)/60)^2 = P

....
Now just plug in EI to the equation and you'll get P.
To use it correctly in matlab, you will want to flip the equation such
that P is on the lhs
P = EI*(asec(2.2)/60)^2

Does that make sense?

-Nathan
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