quickFactor

README

Quick Factor

Command-line tool to find factors of a polynomial function.

Installation

This program can be installed two different ways:

1. With Golang installed

• Open a command line
• Run go get github.com/noah-friedman/find-factors/cmd/find-factors (NOTE: You must have $GOPATH/bin in the system path)
• Run the program by running find-factors on the command line

2. Without Golang installed

• Navigate to the releases page
• Download the correct binary for your system from the latest release
• macOS and Linux only: Run chmod +x path/to/binary in order to mark the binary as executable
• Run the executable file

Documentation

Overview

Define types and functions related to factoring.

Define the Polynomial type and its methods.

Index

• type FactoredPolynomial
  • func Factor(unfactored Polynomial, roundTo int) *FactoredPolynomial
• type Polynomial
  • func (p *Polynomial) Degree() int
  • func (p *Polynomial) F(x float64) float64

Examples

• Factor (LongPolynomial)
• Factor (QuadraticFormula)
• Factor (SimpleTrinomial)
• Polynomial.Degree
• Polynomial.F

Types

type FactoredPolynomial

type FactoredPolynomial struct {
	Raw         string
	XIntercepts []float64
	Unfactored  Polynomial
}

A polynomial in factored form.

func Factor

func Factor(unfactored Polynomial, roundTo int) *FactoredPolynomial

Factor a polynomial function. Round numbers displayed in the 'Raw' field to 'roundTo' decimal places. If the function is not factorable, the 'Raw' field will read "not factorable".

Example (LongPolynomial)

p := Polynomial{1, -4, 0, 7, 2} // 2x⁴ + 7x³ - 4x + 1

f := Factor(p, 2)
fmt.Println(f.Raw) 

Output:
(x + 1)(x - 0.5)(x - 0.3)(x + 3.3)

Example (QuadraticFormula)

p := Polynomial{10, 2, 1} // x² + 2x + 10

f := Factor(p, 2)
fmt.Println(f.Raw) 

Output:
(x - ((-2 + √-36) / 2))(x - ((-2 - √-36) / 2))

Example (SimpleTrinomial)

p := Polynomial{10, 7, 1} // x² + 7x + 10

f := Factor(p, 2)
fmt.Println(f.Raw) 

Output:
(x + 5)(x + 2)

type Polynomial

type Polynomial []float64

A type that represents a polynomial function. Each array index is mapped to the corresponding term. For example,

Polynomial{5, -13, 1, 4}

Index:     0    1  2  3

represents the polynomial function:

            x³ + x² - 13x + 5

Power of x: 3    2      1   0

func (*Polynomial) Degree

func (p *Polynomial) Degree() int

Returns the degree (highest exponent) of the polynomial function.

Example

p := Polynomial{5, -12, 4}
// 4x² - 12x + 5 --> highest exponent = 2

fmt.Print(p.Degree()) 

Output:
2

func (*Polynomial) F

func (p *Polynomial) F(x float64) float64

Find the value of the polynomial function using the provided 'x' value.

Example

x := 7.0
p := Polynomial{3, 5}
// 5x + 3 -> 5(7) + 3 == 38

fmt.Print(p.F(x)) 

Output:
38