fit

package
v0.17.0 Latest Latest
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 Go to latest Published: Dec 22, 2018 License: BSD-3-Clause, BSD-3-Clause Imports: 4 Imported by: 4

README

fit

GoDoc

fit is a WIP package to provide easy fitting models and curve fitting functions.

H1D

Fit a gaussian

h1d-gaussian-example

func ExampleH1D_gaussian() {
	var (
		mean  = 2.0
		sigma = 4.0
		// Values from gonum/optimize:
		want = []float64{447.0483517081991, 2.02127773281178, 3.9965893891862687}
		// Values from ROOT:
		// want  = []float64{4.53720e+02, 1.93218e+00, 3.93188e+00}
	)

	const npoints = 10000

	// Create a normal distribution.
	dist := distuv.Normal{
		Mu:    mean,
		Sigma: sigma,
		Src:   rand.New(rand.NewSource(0)),
	}

	// Draw some random values from the standard
	// normal distribution.
	hist := hbook.NewH1D(100, -20, +25)
	for i := 0; i < npoints; i++ {
		v := dist.Rand()
		hist.Fill(v, 1)
	}

	gauss := func(x, cst, mu, sigma float64) float64 {
		v := (x - mu) / sigma
		return cst * math.Exp(-0.5*v*v)
	}

	res, err := fit.H1D(
		hist,
		fit.Func1D{
			F: func(x float64, ps []float64) float64 {
				return gauss(x, ps[0], ps[1], ps[2])
			},
			N: len(want),
		},
		nil, &optimize.NelderMead{},
	)
	if err != nil {
		log.Fatal(err)
	}

	if err := res.Status.Err(); err != nil {
		log.Fatal(err)
	}
	if got := res.X; !floats.EqualApprox(got, want, 1e-3) {
		log.Fatalf("got= %v\nwant=%v\n", got, want)
	}

	{
		p := hplot.New()
		p.X.Label.Text = "f(x) = cst * exp(-0.5 * ((x-mu)/sigma)^2)"
		p.Y.Label.Text = "y-data"
		p.Y.Min = 0

		h := hplot.NewH1D(hist)
		h.Color = color.RGBA{0, 0, 255, 255}
		p.Add(h)

		f := plotter.NewFunction(func(x float64) float64 {
			return gauss(x, res.X[0], res.X[1], res.X[2])
		})
		f.Color = color.RGBA{255, 0, 0, 255}
		f.Samples = 1000
		p.Add(f)

		p.Add(plotter.NewGrid())

		err := p.Save(20*vg.Centimeter, -1, "testdata/h1d-gauss-plot.png")
		if err != nil {
			log.Fatal(err)
		}
	}
}

Curve1D

Fit a gaussian

func1d-gaussian-example

func ExampleCurve1D_gaussian() {
	var (
		cst   = 3.0
		mean  = 30.0
		sigma = 20.0
		want  = []float64{cst, mean, sigma}
	)

	xdata, ydata, err := readXY("testdata/gauss-data.txt")
	if err != nil {
		log.Fatal(err)
	}

	gauss := func(x, cst, mu, sigma float64) float64 {
		v := (x - mu)
		return cst * math.Exp(-v*v/sigma)
	}

	res, err := fit.Curve1D(
		fit.Func1D{
			F: func(x float64, ps []float64) float64 {
				return gauss(x, ps[0], ps[1], ps[2])
			},
			X:  xdata,
			Y:  ydata,
			Ps: []float64{10, 10, 10},
		},
		nil, &optimize.NelderMead{},
	)
	if err != nil {
		log.Fatal(err)
	}

	if err := res.Status.Err(); err != nil {
		log.Fatal(err)
	}
	if got := res.X; !floats.EqualApprox(got, want, 1e-3) {
		log.Fatalf("got= %v\nwant=%v\n", got, want)
	}

	{
		p := hplot.New()
		p.X.Label.Text = "Gauss"
		p.Y.Label.Text = "y-data"

		s := hplot.NewS2D(hplot.ZipXY(xdata, ydata))
		s.Color = color.RGBA{0, 0, 255, 255}
		p.Add(s)

		f := plotter.NewFunction(func(x float64) float64 {
			return gauss(x, res.X[0], res.X[1], res.X[2])
		})
		f.Color = color.RGBA{255, 0, 0, 255}
		f.Samples = 1000
		p.Add(f)

		p.Add(plotter.NewGrid())

		err := p.Save(20*vg.Centimeter, -1, "testdata/gauss-plot.png")
		if err != nil {
			log.Fatal(err)
		}
	}
}
Fit a powerlaw (with Y-errors)

func1d-powerlaw-example

func ExampleCurve1D_powerlaw() {
	var (
		amp   = 11.021171432949746
		index = -2.027389113217428
		want  = []float64{amp, index}
	)

	xdata, ydata, yerrs, err := readXYerr("testdata/powerlaw-data.txt")
	if err != nil {
		log.Fatal(err)
	}

	plaw := func(x, amp, index float64) float64 {
		return amp * math.Pow(x, index)
	}

	res, err := fit.Curve1D(
		fit.Func1D{
			F: func(x float64, ps []float64) float64 {
				return plaw(x, ps[0], ps[1])
			},
			X:   xdata,
			Y:   ydata,
			Err: yerrs,
			Ps:  []float64{1, 1},
		},
		nil, &optimize.NelderMead{},
	)
	if err != nil {
		log.Fatal(err)
	}

	if err := res.Status.Err(); err != nil {
		log.Fatal(err)
	}
	if got := res.X; !floats.EqualApprox(got, want, 1e-3) {
		log.Fatalf("got= %v\nwant=%v\n", got, want)
	}

	{
		p := hplot.New()
		p.X.Label.Text = "f(x) = a * x^b"
		p.Y.Label.Text = "y-data"
		p.X.Min = 0
		p.X.Max = 10
		p.Y.Min = 0
		p.Y.Max = 10

		pts := make([]hbook.Point2D, len(xdata))
		for i := range pts {
			pts[i].X = xdata[i]
			pts[i].Y = ydata[i]
			pts[i].ErrY.Min = 0.5 * yerrs[i]
			pts[i].ErrY.Max = 0.5 * yerrs[i]
		}

		s := hplot.NewS2D(hbook.NewS2D(pts...), hplot.WithYErrBars)
		s.Color = color.RGBA{0, 0, 255, 255}
		p.Add(s)

		f := plotter.NewFunction(func(x float64) float64 {
			return plaw(x, res.X[0], res.X[1])
		})
		f.Color = color.RGBA{255, 0, 0, 255}
		f.Samples = 1000
		p.Add(f)

		p.Add(plotter.NewGrid())

		err := p.Save(20*vg.Centimeter, -1, "testdata/powerlaw-plot.png")
		if err != nil {
			log.Fatal(err)
		}
	}
}
Fit an exponential

func1d-exp-example

func ExampleCurve1D_exponential() {
	const (
		a   = 0.3
		b   = 0.1
		ndf = 2.0
	)

	xdata, ydata, err := readXY("testdata/exp-data.txt")
	if err != nil {
		log.Fatal(err)
	}

	exp := func(x, a, b float64) float64 {
		return math.Exp(a*x + b)
	}

	res, err := fit.Curve1D(
		fit.Func1D{
			F: func(x float64, ps []float64) float64 {
				return exp(x, ps[0], ps[1])
			},
			X: xdata,
			Y: ydata,
			N: 2,
		},
		nil, &optimize.NelderMead{},
	)
	if err != nil {
		log.Fatal(err)
	}

	if err := res.Status.Err(); err != nil {
		log.Fatal(err)
	}
	if got, want := res.X, []float64{a, b}; !floats.EqualApprox(got, want, 0.1) {
		log.Fatalf("got= %v\nwant=%v\n", got, want)
	}

	{
		p := hplot.New()
		p.X.Label.Text = "exp(a*x+b)"
		p.Y.Label.Text = "y-data"
		p.Y.Min = 0
		p.Y.Max = 5
		p.X.Min = 0
		p.X.Max = 5

		s := hplot.NewS2D(hplot.ZipXY(xdata, ydata))
		s.Color = color.RGBA{0, 0, 255, 255}
		p.Add(s)

		f := plotter.NewFunction(func(x float64) float64 {
			return exp(x, res.X[0], res.X[1])
		})
		f.Color = color.RGBA{255, 0, 0, 255}
		f.Samples = 1000
		p.Add(f)

		p.Add(plotter.NewGrid())

		err := p.Save(20*vg.Centimeter, -1, "testdata/exp-plot.png")
		if err != nil {
			log.Fatal(err)
		}
	}
}
Fit a polynomial

func1d-poly-example

func ExampleCurve1D_poly() {
	var (
		a    = 1.0
		b    = 2.0
		ps   = []float64{a, b}
		want = []float64{1.38592513, 1.98485122} // from scipy.curve_fit
	)

	poly := func(x float64, ps []float64) float64 {
		return ps[0] + ps[1]*x*x
	}

	xdata, ydata := genXY(100, poly, ps, -10, 10)

	res, err := fit.Curve1D(
		fit.Func1D{
			F:  poly,
			X:  xdata,
			Y:  ydata,
			Ps: []float64{1, 1},
		},
		nil, &optimize.NelderMead{},
	)
	if err != nil {
		log.Fatal(err)
	}

	if err := res.Status.Err(); err != nil {
		log.Fatal(err)
	}

	if got := res.X; !floats.EqualApprox(got, want, 1e-6) {
		log.Fatalf("got= %v\nwant=%v\n", got, want)
	}

	{
		p := hplot.New()
		p.X.Label.Text = "f(x) = a + b*x*x"
		p.Y.Label.Text = "y-data"
		p.X.Min = -10
		p.X.Max = +10
		p.Y.Min = 0
		p.Y.Max = 220

		s := hplot.NewS2D(hplot.ZipXY(xdata, ydata))
		s.Color = color.RGBA{0, 0, 255, 255}
		p.Add(s)

		f := plotter.NewFunction(func(x float64) float64 {
			return poly(x, res.X)
		})
		f.Color = color.RGBA{255, 0, 0, 255}
		f.Samples = 1000
		p.Add(f)

		p.Add(plotter.NewGrid())

		err := p.Save(20*vg.Centimeter, -1, "testdata/poly-plot.png")
		if err != nil {
			log.Fatal(err)
		}
	}
}

Documentation

Overview

Package fit provides functions to fit data.

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func Curve1D 

func Curve1D(f Func1D, settings *optimize.Settings, m optimize.Method) (*optimize.Result, error)

Curve1D returns the result of a non-linear least squares to fit a function f to the underlying data with method m.

Example (Exponential) 
package main

import (
	"bufio"
	"image/color"
	"log"
	"math"
	"os"
	"strconv"
	"strings"

	"go-hep.org/x/hep/fit"
	"go-hep.org/x/hep/hplot"
	"gonum.org/v1/gonum/floats"
	"gonum.org/v1/gonum/optimize"
	"gonum.org/v1/plot/plotter"
	"gonum.org/v1/plot/vg"
)

func main() {
	const (
		a   = 0.3
		b   = 0.1
		ndf = 2.0
	)

	xdata, ydata, err := readXY("testdata/exp-data.txt")
	if err != nil {
		log.Fatal(err)
	}

	exp := func(x, a, b float64) float64 {
		return math.Exp(a*x + b)
	}

	res, err := fit.Curve1D(
		fit.Func1D{
			F: func(x float64, ps []float64) float64 {
				return exp(x, ps[0], ps[1])
			},
			X: xdata,
			Y: ydata,
			N: 2,
		},
		nil, &optimize.NelderMead{},
	)
	if err != nil {
		log.Fatal(err)
	}

	if err := res.Status.Err(); err != nil {
		log.Fatal(err)
	}
	if got, want := res.X, []float64{a, b}; !floats.EqualApprox(got, want, 0.1) {
		log.Fatalf("got= %v\nwant=%v\n", got, want)
	}

	{
		p := hplot.New()
		p.X.Label.Text = "exp(a*x+b)"
		p.Y.Label.Text = "y-data"
		p.Y.Min = 0
		p.Y.Max = 5
		p.X.Min = 0
		p.X.Max = 5

		s := hplot.NewS2D(hplot.ZipXY(xdata, ydata))
		s.Color = color.RGBA{0, 0, 255, 255}
		p.Add(s)

		f := plotter.NewFunction(func(x float64) float64 {
			return exp(x, res.X[0], res.X[1])
		})
		f.Color = color.RGBA{255, 0, 0, 255}
		f.Samples = 1000
		p.Add(f)

		p.Add(plotter.NewGrid())

		err := p.Save(20*vg.Centimeter, -1, "testdata/exp-plot.png")
		if err != nil {
			log.Fatal(err)
		}
	}
}

func readXY(fname string) (xs, ys []float64, err error) {
	f, err := os.Open(fname)
	if err != nil {
		return xs, ys, err
	}
	defer f.Close()

	scan := bufio.NewScanner(f)
	for scan.Scan() {
		line := scan.Text()
		toks := strings.Split(line, " ")
		x, err := strconv.ParseFloat(toks[0], 64)
		if err != nil {
			return xs, ys, err
		}
		xs = append(xs, x)

		y, err := strconv.ParseFloat(toks[1], 64)
		if err != nil {
			return xs, ys, err
		}
		ys = append(ys, y)
	}

	return
}

Output:
Example (Gaussian) 
package main

import (
	"bufio"
	"image/color"
	"log"
	"math"
	"os"
	"strconv"
	"strings"

	"go-hep.org/x/hep/fit"
	"go-hep.org/x/hep/hplot"
	"gonum.org/v1/gonum/floats"
	"gonum.org/v1/gonum/optimize"
	"gonum.org/v1/plot/plotter"
	"gonum.org/v1/plot/vg"
)

func main() {
	var (
		cst   = 3.0
		mean  = 30.0
		sigma = 20.0
		want  = []float64{cst, mean, sigma}
	)

	xdata, ydata, err := readXY("testdata/gauss-data.txt")
	if err != nil {
		log.Fatal(err)
	}

	gauss := func(x, cst, mu, sigma float64) float64 {
		v := (x - mu)
		return cst * math.Exp(-v*v/sigma)
	}

	res, err := fit.Curve1D(
		fit.Func1D{
			F: func(x float64, ps []float64) float64 {
				return gauss(x, ps[0], ps[1], ps[2])
			},
			X:  xdata,
			Y:  ydata,
			Ps: []float64{10, 10, 10},
		},
		nil, &optimize.NelderMead{},
	)
	if err != nil {
		log.Fatal(err)
	}

	if err := res.Status.Err(); err != nil {
		log.Fatal(err)
	}
	if got := res.X; !floats.EqualApprox(got, want, 1e-3) {
		log.Fatalf("got= %v\nwant=%v\n", got, want)
	}

	{
		p := hplot.New()
		p.X.Label.Text = "Gauss"
		p.Y.Label.Text = "y-data"

		s := hplot.NewS2D(hplot.ZipXY(xdata, ydata))
		s.Color = color.RGBA{0, 0, 255, 255}
		p.Add(s)

		f := plotter.NewFunction(func(x float64) float64 {
			return gauss(x, res.X[0], res.X[1], res.X[2])
		})
		f.Color = color.RGBA{255, 0, 0, 255}
		f.Samples = 1000
		p.Add(f)

		p.Add(plotter.NewGrid())

		err := p.Save(20*vg.Centimeter, -1, "testdata/gauss-plot.png")
		if err != nil {
			log.Fatal(err)
		}
	}
}

func readXY(fname string) (xs, ys []float64, err error) {
	f, err := os.Open(fname)
	if err != nil {
		return xs, ys, err
	}
	defer f.Close()

	scan := bufio.NewScanner(f)
	for scan.Scan() {
		line := scan.Text()
		toks := strings.Split(line, " ")
		x, err := strconv.ParseFloat(toks[0], 64)
		if err != nil {
			return xs, ys, err
		}
		xs = append(xs, x)

		y, err := strconv.ParseFloat(toks[1], 64)
		if err != nil {
			return xs, ys, err
		}
		ys = append(ys, y)
	}

	return
}

Output:
Example (Poly) 
package main

import (
	"image/color"
	"log"
	"math/rand"

	"go-hep.org/x/hep/fit"
	"go-hep.org/x/hep/hplot"
	"gonum.org/v1/gonum/floats"
	"gonum.org/v1/gonum/optimize"
	"gonum.org/v1/plot/plotter"
	"gonum.org/v1/plot/vg"
)

func main() {
	var (
		a    = 1.0
		b    = 2.0
		ps   = []float64{a, b}
		want = []float64{1.38592513, 1.98485122} // from scipy.curve_fit
	)

	poly := func(x float64, ps []float64) float64 {
		return ps[0] + ps[1]*x*x
	}

	xdata, ydata := genXY(100, poly, ps, -10, 10)

	res, err := fit.Curve1D(
		fit.Func1D{
			F:  poly,
			X:  xdata,
			Y:  ydata,
			Ps: []float64{1, 1},
		},
		nil, &optimize.NelderMead{},
	)
	if err != nil {
		log.Fatal(err)
	}

	if err := res.Status.Err(); err != nil {
		log.Fatal(err)
	}

	if got := res.X; !floats.EqualApprox(got, want, 1e-6) {
		log.Fatalf("got= %v\nwant=%v\n", got, want)
	}

	{
		p := hplot.New()
		p.X.Label.Text = "f(x) = a + b*x*x"
		p.Y.Label.Text = "y-data"
		p.X.Min = -10
		p.X.Max = +10
		p.Y.Min = 0
		p.Y.Max = 220

		s := hplot.NewS2D(hplot.ZipXY(xdata, ydata))
		s.Color = color.RGBA{0, 0, 255, 255}
		p.Add(s)

		f := plotter.NewFunction(func(x float64) float64 {
			return poly(x, res.X)
		})
		f.Color = color.RGBA{255, 0, 0, 255}
		f.Samples = 1000
		p.Add(f)

		p.Add(plotter.NewGrid())

		err := p.Save(20*vg.Centimeter, -1, "testdata/poly-plot.png")
		if err != nil {
			log.Fatal(err)
		}
	}
}

func genXY(n int, f func(x float64, ps []float64) float64, ps []float64, xmin, xmax float64) ([]float64, []float64) {
	xdata := make([]float64, n)
	ydata := make([]float64, n)
	rnd := rand.New(rand.NewSource(1234))
	xstep := (xmax - xmin) / float64(n)
	p := make([]float64, len(ps))
	for i := 0; i < n; i++ {
		x := xmin + xstep*float64(i)
		for j := range p {
			v := rnd.NormFloat64()
			p[j] = ps[j] + v*0.2
		}
		xdata[i] = x
		ydata[i] = f(x, p)
	}
	return xdata, ydata
}

Output:
Example (Powerlaw) 
package main

import (
	"bufio"
	"image/color"
	"log"
	"math"
	"os"
	"strconv"
	"strings"

	"go-hep.org/x/hep/fit"
	"go-hep.org/x/hep/hbook"
	"go-hep.org/x/hep/hplot"
	"gonum.org/v1/gonum/floats"
	"gonum.org/v1/gonum/optimize"
	"gonum.org/v1/plot/plotter"
	"gonum.org/v1/plot/vg"
)

func main() {
	var (
		amp   = 11.021171432949746
		index = -2.027389113217428
		want  = []float64{amp, index}
	)

	xdata, ydata, yerrs, err := readXYerr("testdata/powerlaw-data.txt")
	if err != nil {
		log.Fatal(err)
	}

	plaw := func(x, amp, index float64) float64 {
		return amp * math.Pow(x, index)
	}

	res, err := fit.Curve1D(
		fit.Func1D{
			F: func(x float64, ps []float64) float64 {
				return plaw(x, ps[0], ps[1])
			},
			X:   xdata,
			Y:   ydata,
			Err: yerrs,
			Ps:  []float64{1, 1},
		},
		nil, &optimize.NelderMead{},
	)
	if err != nil {
		log.Fatal(err)
	}

	if err := res.Status.Err(); err != nil {
		log.Fatal(err)
	}
	if got := res.X; !floats.EqualApprox(got, want, 1e-3) {
		log.Fatalf("got= %v\nwant=%v\n", got, want)
	}

	{
		p := hplot.New()
		p.X.Label.Text = "f(x) = a * x^b"
		p.Y.Label.Text = "y-data"
		p.X.Min = 0
		p.X.Max = 10
		p.Y.Min = 0
		p.Y.Max = 10

		pts := make([]hbook.Point2D, len(xdata))
		for i := range pts {
			pts[i].X = xdata[i]
			pts[i].Y = ydata[i]
			pts[i].ErrY.Min = 0.5 * yerrs[i]
			pts[i].ErrY.Max = 0.5 * yerrs[i]
		}

		s := hplot.NewS2D(hbook.NewS2D(pts...), hplot.WithYErrBars)
		s.Color = color.RGBA{0, 0, 255, 255}
		p.Add(s)

		f := plotter.NewFunction(func(x float64) float64 {
			return plaw(x, res.X[0], res.X[1])
		})
		f.Color = color.RGBA{255, 0, 0, 255}
		f.Samples = 1000
		p.Add(f)

		p.Add(plotter.NewGrid())

		err := p.Save(20*vg.Centimeter, -1, "testdata/powerlaw-plot.png")
		if err != nil {
			log.Fatal(err)
		}
	}
}

func readXYerr(fname string) (xs, ys, yerrs []float64, err error) {
	f, err := os.Open(fname)
	if err != nil {
		return xs, ys, yerrs, err
	}
	defer f.Close()

	scan := bufio.NewScanner(f)
	for scan.Scan() {
		line := scan.Text()
		toks := strings.Split(line, " ")
		x, err := strconv.ParseFloat(toks[0], 64)
		if err != nil {
			return xs, ys, yerrs, err
		}
		xs = append(xs, x)

		y, err := strconv.ParseFloat(toks[1], 64)
		if err != nil {
			return xs, ys, yerrs, err
		}
		ys = append(ys, y)

		yerr, err := strconv.ParseFloat(toks[2], 64)
		if err != nil {
			return xs, ys, yerrs, err
		}
		yerrs = append(yerrs, yerr)
	}

	return
}

Output:

func H1D 

func H1D(h *hbook.H1D, f Func1D, settings *optimize.Settings, m optimize.Method) (*optimize.Result, error)

H1D returns the fit of histogram h with function f and optimization method m.

Only bins with at least an entry are considered for the fit. In case settings is nil, the optimize.DefaultSettingsLocal is used. In case m is nil, the same default optimization method than for Curve1D is used.

Example (Gaussian) 
package main

import (
	"image/color"
	"log"
	"math"

	"go-hep.org/x/hep/fit"
	"go-hep.org/x/hep/hbook"
	"go-hep.org/x/hep/hplot"
	"golang.org/x/exp/rand"
	"gonum.org/v1/gonum/floats"
	"gonum.org/v1/gonum/optimize"
	"gonum.org/v1/gonum/stat/distuv"
	"gonum.org/v1/plot/plotter"
	"gonum.org/v1/plot/vg"
)

func main() {
	var (
		mean  = 2.0
		sigma = 4.0
		// Values from gonum/optimize:
		want = []float64{447.0483517081991, 2.02127773281178, 3.9965893891862687}
		// Values from ROOT:
		// want  = []float64{4.53720e+02, 1.93218e+00, 3.93188e+00}
	)

	const npoints = 10000

	// Create a normal distribution.
	dist := distuv.Normal{
		Mu:    mean,
		Sigma: sigma,
		Src:   rand.New(rand.NewSource(0)),
	}

	// Draw some random values from the standard
	// normal distribution.
	hist := hbook.NewH1D(100, -20, +25)
	for i := 0; i < npoints; i++ {
		v := dist.Rand()
		hist.Fill(v, 1)
	}

	gauss := func(x, cst, mu, sigma float64) float64 {
		v := (x - mu) / sigma
		return cst * math.Exp(-0.5*v*v)
	}

	res, err := fit.H1D(
		hist,
		fit.Func1D{
			F: func(x float64, ps []float64) float64 {
				return gauss(x, ps[0], ps[1], ps[2])
			},
			N: len(want),
		},
		nil, &optimize.NelderMead{},
	)
	if err != nil {
		log.Fatal(err)
	}

	if err := res.Status.Err(); err != nil {
		log.Fatal(err)
	}
	if got := res.X; !floats.EqualApprox(got, want, 1e-3) {
		log.Fatalf("got= %v\nwant=%v\n", got, want)
	}

	{
		p := hplot.New()
		p.X.Label.Text = "f(x) = cst * exp(-0.5 * ((x-mu)/sigma)^2)"
		p.Y.Label.Text = "y-data"
		p.Y.Min = 0

		h := hplot.NewH1D(hist)
		h.Color = color.RGBA{0, 0, 255, 255}
		p.Add(h)

		f := plotter.NewFunction(func(x float64) float64 {
			return gauss(x, res.X[0], res.X[1], res.X[2])
		})
		f.Color = color.RGBA{255, 0, 0, 255}
		f.Samples = 1000
		p.Add(f)

		p.Add(plotter.NewGrid())

		err := p.Save(20*vg.Centimeter, -1, "testdata/h1d-gauss-plot.png")
		if err != nil {
			log.Fatal(err)
		}
	}
}

Output:

Types

type Func1D 

type Func1D struct {
	// F is the function to minimize.
	// ps is the slice of parameters to optimize during the fit.
	F func(x float64, ps []float64) float64

	// N is the number of parameters to optimize during the fit.
	// If N is 0, Ps must not be nil.
	N int

	// Ps is the initial values for the parameters.
	// If Ps is nil, the set of initial parameters values is a slice of
	// length N filled with zeros.
	Ps []float64

	X   []float64
	Y   []float64
	Err []float64
	// contains filtered or unexported fields
}

Func1D describes a 1D function to fit some data.

Source Files

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