nero1701
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| posted on 24/8/18 at 08:04 AM |
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Using Excel to solve simultaneous Equations
So.....
I'm trying to use Excel to solve simultaneous equations, being more precise Kirchoffs
So, example
If I have a pair of loops,
6*I1+4*I2=4 (EQ1)
4*I1+5*I2=2 (EQ2)
How would I get the answer outputted on Excel..
Ive been playing with Minverse and Mmult but am struggling..
Any help appreciated
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02GF74
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| posted on 24/8/18 at 11:13 AM |
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Write i2 in terms of i1 (eq1) and substitute in eq2.
Why do you need excel to do something as simple as that?
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nero1701
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| posted on 24/8/18 at 11:27 AM |
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I want to be able to give 20 different values for the values of resistors as well as changing values of voltages.
Stop my students copying each other and stop me writing 20 sets of solutions.
The simultaneous equations are not the problem. It’s the copying!!!
[Edited on 24/8/18 by nero1701]
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02GF74
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| posted on 24/8/18 at 11:48 AM |
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OK, that is different question to originally posted and makes it clearer what you are trying to achieve.
Disclaimer. I am no excel expert.
But it looks to me you need a column for r1, r2, (in e1), (r3, r4 if
Different in e2), v1 and v2.
Then two more columns for i1 and i2. These will use the above cformulas, one of which needs to have one I value substituted as in my previous post,
and make use of the columns for the resistor and voltage values for the given row.
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on_eighty_runner
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| posted on 25/8/18 at 06:10 PM |
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as said before you need to create some columns to generate the resistor and voltage values and solve current based on that.
6*I1+4*I2=4 (EQ1)
4*I1+5*I2=2 (EQ2)
To this:
A.I1+B.I2 = C (EQ1)
D.I1+E.I2=F (EQ2)
where A=6, B=4, C=4 etc
and isolate I2. from EQ2
E.I2 = F-D.I1
{I2 = (F-D.I1)/E}
back to EQ1
A.I1+B.{(F-D.I1)/E}=C
E.A.I1+BF-DB.I1= C.E
E.A.I1-DB.I1= C.E- B.F
I1.(E.A-B.D) = C.E - B.F
so I1 = (C.E - B.F) / (E.A-B.D)
I2 can be solved in exactly the same but opposite approach. { check the algebra, I typically work on paper!}
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