cscalar

Documentation

Overview

Package cscalar provides a set of helper routines for dealing with complex128 values.

Index

• func EqualWithinAbs(a, b complex128, tol float64) bool
• func EqualWithinAbsOrRel(a, b complex128, absTol, relTol float64) bool
• func EqualWithinRel(a, b complex128, tol float64) bool
• func ParseWithNA(s, missing string) (value complex128, weight float64, err error)
• func Round(x complex128, prec int) complex128
• func RoundEven(x complex128, prec int) complex128
• func Same(a, b complex128) bool

Examples

• ParseWithNA

Functions

func EqualWithinAbs

func EqualWithinAbs(a, b complex128, tol float64) bool

EqualWithinAbs returns true when a and b have an absolute difference not greater than tol.

func EqualWithinAbsOrRel

func EqualWithinAbsOrRel(a, b complex128, absTol, relTol float64) bool

EqualWithinAbsOrRel returns true when a and b are equal to within the absolute or relative tolerances. See EqualWithinAbs and EqualWithinRel for details.

func EqualWithinRel

func EqualWithinRel(a, b complex128, tol float64) bool

EqualWithinRel returns true when the difference between a and b is not greater than tol times the greater absolute value of a and b,

abs(a-b) <= tol * max(abs(a), abs(b)).

func ParseWithNA

func ParseWithNA(s, missing string) (value complex128, weight float64, err error)

ParseWithNA converts the string s to a complex128 in value. If s equals missing, weight is returned as 0, otherwise 1.

Example

package main

import (
	"bufio"
	"fmt"
	"log"
	"strings"

	"gonum.org/v1/gonum/cmplxs"
	"gonum.org/v1/gonum/cmplxs/cscalar"
	"gonum.org/v1/gonum/floats"
)

func main() {
	// Calculate the mean of a list of numbers
	// ignoring missing values.
	const data = `6+2i
missing
4-4i
`

	var (
		vals    []complex128
		weights []float64
	)
	sc := bufio.NewScanner(strings.NewReader(data))
	for sc.Scan() {
		v, w, err := cscalar.ParseWithNA(sc.Text(), "missing")
		if err != nil {
			log.Fatal(err)
		}
		vals = append(vals, v)
		weights = append(weights, w)
	}
	err := sc.Err()
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(cmplxs.Sum(vals) / complex(floats.Sum(weights), 0))

}

Output:

(5-1i)

func Round

func Round(x complex128, prec int) complex128

Round returns the half away from zero rounded value of x with prec precision.

Special cases are:

Round(±0) = +0
Round(±Inf) = ±Inf
Round(NaN) = NaN

func RoundEven

func RoundEven(x complex128, prec int) complex128

RoundEven returns the half even rounded value of x with prec precision.

Special cases are:

RoundEven(±0) = +0
RoundEven(±Inf) = ±Inf
RoundEven(NaN) = NaN

func Same

func Same(a, b complex128) bool

Same returns true when the inputs have the same value, allowing NaN equality.