quad: Solve Quadratic Equation for Positive Real Roots
Description
This function solves a quadratic equation of the form `ax^2 + bx + c = 0`
and returns only the positive real roots. It handles complex intermediate
calculations and returns real numbers if the roots are real.
Usage
quad(a = 3, b = 2, c = -1)
Value
A numeric vector containing the positive real root(s) of the quadratic equation.
Returns `numeric(0)` if no positive real roots are found.
Returns a single value if both positive roots are identical.