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Author Comment/Response
Peter Pein
04/02/13 4:09pm

Hi,

the following will define a function that returns all values of q for given parameters:

calcq[l1_, l2_, d1_, d2_, h1_, h2_] :=
Block[{q, q1, q2},
q /. Solve[
{h1 == 31/12500 (((l1 + l2) q^2)/(d1 + d2)^5 + (l1 q1^2)/d1^5),
h2 == 31 /12500 (((l1 + l2) q^2)/(d1 + d2)^5 + (l2 q2^2)/d2^5),
q == q1 + q2}, q, {q1, q2}]]

means : given parameters l1,l2,..,h2 calculate the values of q that solve the three equations while eliminating q1 and q2

calcq[500, 300, 15/100, 1/10, 25, 30] // Simplify

{-(25/32) Sqrt[(15 (15205433 - 54000 Sqrt[47591]))/89426826199],
25/32 Sqrt[(15 (15205433 - 54000 Sqrt[47591]))/89426826199],
-(25/32) Sqrt[(15 (15205433 + 54000 Sqrt[47591]))/89426826199],
25/32 Sqrt[(15 (15205433 + 54000 Sqrt[47591]))/89426826199]}

get the approximate values:
N[%, 16]

{-0.01872581690517561, 0.01872581690517561,
-0.05256162970072469, 0.05256162970072469}

Peter

P.S.:
try for example:

Plot[calcq[x1, 800 - x1, 15/100, 1/10, 25, 30] // Evaluate,
{x1, 0, 800}]

URL: ,

Subject (listing for 'Equation System')
Author Date Posted
Equation System Marc 04/02/13 07:26am
Re: Equation System jf 04/02/13 10:23am
Re: Equation System Bill Simpson 04/02/13 11:52am
Re: Equation System Peter Pein 04/02/13 4:09pm
Re: Equation System Marc 04/03/13 02:15am
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