# How can I infer the solutions of a specific polynomial?

1 view (last 30 days)
Jonas Morgner on 4 May 2022
Edited: Matt J on 4 May 2022
% A
v1 = [1 -2 -5 6] % Storing the values of the polynomial
% B
v2 = [-100 : .1 : 100] % Sequencing the numbers in .1 steps
% C
y = polyval (v1, v2) % Polyval function
plot(v2, y) % Plotting
How can I infer the solutions of the polynomial?

Matt J on 4 May 2022
Edited: Matt J on 4 May 2022
By "solutions", do you mean the roots? Just use the roots command.
v1 = [1 -2 -5 6] ;
roots(v1)
ans = 3×1
-2.0000 3.0000 1.0000
Walter Roberson on 4 May 2022
v1 = [1 -2 -5 6]
v1 = 1×4
1 -2 -5 6
r = roots(v1)
r = 3×1
-2.0000 3.0000 1.0000
mask = imag(r) ~= 0 | real(r) < -100 | real(r) > 100; %remove anything not in -100 to +100
r = 3×1
-2.0000 3.0000 1.0000
r
r = 3×1
-2.0000 3.0000 1.0000

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