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Linear Algebra and its Applications
- Circuit
Analysis -
One important linear
algebra application
is the resolution of electrical circuits.
We can describe this type of circuits with linear equations, and then
we can solve the linear
system using Matlab.
For
example, let's examine the following electrical circuit (resistors are
in ohms, currents in amperes, and voltages are in volts):
We can describe the circuit with the following system of linear
equations:
7 - 1(i1 - i2) - 6 - 2(i1 - i3) = 0
-1(i2 - i1) - 2(i2) - 3(i2 - i3) = 0
6 - 3(i3 - i2) - 1(i3) - 2(i3 - i1) = 0
Simplifying and rearranging the equations, we obtain:
-3i1 +
i2
+ 2i3 = -1
i1 - 6i2
+ 3i3 =
0
2i1
+ 3i2 - 6i3 = -6
This system can be described with matrices in the form Ax
= b,
where A
is the matrix of the coefficients of the currents, x
is the vector of unknown currents, and b
is the vector of constants on the right of the equalities.
One
possible Matlab code to solve this is:
A = [-3 1 2
1 -6
3
2
3 -6];
b = [-1 0 -6]';
i = A\b
The Matlab answer is:
i =
3.0000
2.0000
3.0000
>>
This means that i1
= 3, i2 =
2, and i3
= 3.


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