Trapezoid1D

class astropy.modeling.functional_models.Trapezoid1D

Bases: astropy.modeling.Fittable1DModel

One dimensional Trapezoid model.

Parameters:

amplitude : float

Amplitude of the trapezoid

x_0 : float

Center position of the trapezoid

width : float

Width of the constant part of the trapezoid.

slope : float

Slope of the tails of the trapezoid

Other Parameters:  

fixed : a dict

A dictionary {parameter_name: boolean} of parameters to not be varied during fitting. True means the parameter is held fixed. Alternatively the fixed property of a parameter may be used.

tied : dict

A dictionary {parameter_name: callable} of parameters which are linked to some other parameter. The dictionary values are callables providing the linking relationship. Alternatively the tied property of a parameter may be used.

bounds : dict

A dictionary {parameter_name: boolean} of lower and upper bounds of parameters. Keys are parameter names. Values are a list of length 2 giving the desired range for the parameter. Alternatively the min and max properties of a parameter may be used.

eqcons : list

A list of functions of length n such that eqcons[j](x0,*args) == 0.0 in a successfully optimized problem.

ineqcons : list

A list of functions of length n such that ieqcons[j](x0,*args) >= 0.0 is a successfully optimized problem.

See also

Box1D, Gaussian1D, Moffat1D

Examples

import numpy as np
import matplotlib.pyplot as plt

from astropy.modeling.models import Trapezoid1D

plt.figure()
s1 = Trapezoid1D()
r = np.arange(-5, 5, .01)

for factor in range(1, 4):
    s1.amplitude = factor
    s1.width = factor
    plt.plot(r, s1(r), color=str(0.25 * factor), lw=2)

plt.axis([-5, 5, -1, 4])
plt.show()

(Source code, png, hires.png, pdf)

Attributes Summary

amplitude
param_names
slope
width
x_0

Methods Summary

evaluate(x, amplitude, x_0, width, slope)

One dimensional Trapezoid model function

Attributes Documentation

amplitude

param_names = ('amplitude', 'x_0', 'width', 'slope')

slope

width

x_0

Methods Documentation

static evaluate(x, amplitude, x_0, width, slope)

One dimensional Trapezoid model function