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Hi, I really hope you can help me. I have 6 equations...

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Question by Wlotzkas
Submitted on 7/7/2003
Related FAQ: comp.sys.hp48 FAQ : 1 of 4 - Common Questions
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Hi,

I really hope you can help me.

I have 6 equations with 6 unknowns, and would like to solve them using the multiple equation solver of my HP48GX. However, the HP keeps on giving me the message: "Too many unknowns".

The Equations are:
(1)  A=PI*D^2/4*(2*PI-2*THETA)/2/PI+((D/2)^2-(Y-D/2)^2)^.5*(Y-D/2)
(2)   THETA= ACOS((Y-D/2)/(d/2))
(3)   P=PI*D*(2*PI-2*THETA)/2/PI
(4)   R=A/P
(5)   V=-2*(8*9.81*R*S0)^.5*LOG(Ks/14.8/R+0.6275*FI/R/(8*9.81*R*S0)^.5)
(6)   Q=V*A

Unknowns: A, P, R, Y, THETA, V.  (6 Equations, 6 unknowns)

Constants:
Q=0.101 m^3/s
PI=22/7 Dimensionless
D=0.45 m
S0=0.002 m/m
Ks=0.0015 m
FI=1.13E-6 m^2/s

It is in relation to the flow depth of water in a sewer pipe. If I solve y, the answer should be 0.303m.

I saved each equasion in a different name, like A1, P1, etc, and saved { A1 P1 .....} in EQ. Then I pressed MINIT, and then MSOL. All the right vars are there, but I cannot get it to calculate y. However, if I save each equasion under it's var left of the equation mark, (Save V*A in Var Q for example, see equation 6) and solve equation 5 vith the normal equation solver, then I get the right answer. The limitation then is to calculate the other Variables.

Does the MSOL function requires a function that needs to be able to be solver without substitution?

Can you please direct me to anyone that can help me with this if you can't? I will really appreciate it.

Thank you,



Answer by loser
Submitted on 3/17/2004
Rating: Not yet rated Rate this answer: Vote
0123456789 10111213141516171819 20212223242526272829  30313233343536373839 40414243444546474849 50515253545556575859 606162636465676869 70717273747576777879   80818283848586878889 90919293949596979899 100

 

Answer by rt
Submitted on 5/25/2004
Rating: Not yet rated Rate this answer: Vote
2x+3=6

 

Answer by GOD
Submitted on 3/12/2007
Rating: Not yet rated Rate this answer: Vote
you're ass...

 

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