Finds analytical roots to the function y = x^3 + ax^2 + bx + c
Usage
cubic(a, b, c, quiet=FALSE, plot=FALSE)
Arguments
a,b,c
Cubic function coefficients (MONIC FORM).
quiet
If false, the solution is printed to screen.
plot
If true, the function and real root(s) are plotted.
Value
A list with entries for the coefficients, roots, and solution characterization. In particular,
typeThe solution characterization is either "one real", "three real", or "one real, two complex".
coefThe input coefficients c(a,b,c).
rootsA vector for the cubic roots. The first root roots[1] is always real.
If there are complex roots, roots[2] is the real part and roots[3]
is the imaginary part (i.e., complex roots are roots[2] +- roots[3]*i).
Otherwise, roots[2:3] are (possibly identical) real roots.
Details
Finds roots to the cubic function $y = x^3 + ax^2 + bx + c$.