## `polylib::discrim` -- discriminant of a polynomial

#### Introduction

`polylib::discrim``(p, x)` returns the discriminant of the polynomial `p` with respect to the variable `x`.

#### Call(s)

`polylib::discrim(p,x)`

#### Parameters

`x` | - | indeterminante
`p` | - | polynomial or polynomial expression

#### Returns

`polylib::discrim` returns an element of the coefficient ring of `p`. If the coefficient ring is `Expr` or `IntMod(n)`, an expression is returned.

### Overloadable:

`p`

#### Related Functions

`polylib::resultant`

#### Details

- The function `normal` is applied to the discriminant before returning it.

#### Example 1

We compute the discriminant of the general quadratic equation:

    >> polylib::discrim(a*x^2 + b*x + c, x);

                                     2
                                    b  - 4 a c

#### Background

- The discriminant of `p` with respect to the variable `x` is defined as:

      (-1)^(d * (d-1) / 2) * resultant(p, diff(p, x), x) / c

  where d is the degree and c is the leading coefficient of p.

#### Changes

- used to be called `discrim`

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