Learn to solve quadratic equations
We are
going to create now a Matlab program that calculates the quadratic roots (roots
of quadratic
equations). The equation must be in the following form:
ax2
+ bx + c = 0
where a, b, and c are real
coefficients.
The
formula used to calculate the roots is:
Naturally,
we have to deliver two x-values.
The
m-file
that we might use to accomplish this task is very simple:
function
x = rqe(a,b,c)
x(1) =
(-b + sqrt(b^2 - 4 * a * c))/(2*a);
x(2) =
(-b - sqrt(b^2 - 4 * a * c))/(2*a);
We
enter the coefficients as parameters when we call the function. We
assign
to variables x(1)
and x(2)
the calculated values using the formula, and the returning result x
is a
vector containing x(1)
and x(2).
We
could use the following Matlab code instead, to return two separate
variables:
function
[x,y] = rqe2(a,b,c)
x = (-b
+ sqrt(b^2 - 4 * a * c))/(2*a);
y = (-b
- sqrt(b^2 - 4 * a * c))/(2*a);
If we
want to compute the roots of the following expression:
2x2
+ x - 1 = 0
We can
call our function (first code) like this:
x =
rqe(2, 1, -1)
and we
get from Matlab:
x =
0.5000
-1.0000
We can
call our second function (second code above) like this:
[m, n] =
rqe2(2, 1, -1)
and
we
get from Matlab:
m
=
0.5000
n
=
-1
From
'Quadratic
Equations' to
home
From
'Quadratic Equations' to 'Matlab Cookbook'
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