cplot 0.7.0

Plot complex-valued functions

Plot complex-valued functions with style.

cplot helps plotting complex-valued functions in a visually appealing manner.

Install with

pip install cplot

and use as

import numpy as np

import cplot


def f(z):
    return np.sin(z ** 3) / z


plt = cplot.plot(
    f,
    (-2.0, +2.0, 400),
    (-2.0, +2.0, 400),
    # abs_scaling=lambda x: x / (x + 1),  # how to scale the lightness in domain coloring
    # contours_abs="auto",
    # contours_arg=(-np.pi / 2, 0, np.pi / 2, np.pi),
    # dash_abs_contour_1: bool = True,
    # colorspace: str = "cam16",
    # add_colorbars: bool = True,
    # saturation_adjustment: float = 1.28,
)
plt.show()

The plot consists of three building blocks:

• domain coloring, i.e., mapping the absolute value to lightness and the complex argument to the chroma of the representing color
• Contours of constant absolute value (the contour abs(z) == 1 is dashed, the other contours are at (2, 4, 8, etc. and 1/2, 1/4, 1/8, etc., respectively)
• Contours along constant argument (angle). For arg(z) == 0, the color is green, for arg(z) == pi/2 it's orange, for arg(z) = -pi / 2 it's blue, and for arg(z) = pi it's pink

Other useful functions:

# There is a tripcolor function as well for triangulated 2D domains
cplot.tripcolor(triang, z)

# The function get_srgb1 returns the SRGB1 triple for every complex input value.
# (Accepts arrays, too.)
z = 2 + 5j
val = cplot.get_srgb1(z)

Gallery

All plots are created with default settings.

z**1	z**2	z**3

1/z	z / abs(z)	(z+1) / (z-1)

z ** z	(1/z) ** z	z ** (1/z)

np.sqrt	z**(1/3)	z**(1/4)

np.log	np.exp	exp(1/z)

exp(- z ** 2)	1 / (1 + z ** 2)	scipy.special.erf

np.sin	np.cos	np.tan

np.sinh	np.cosh	np.tanh

np.arcsin	np.arccos	np.arctan

sin(z) / z	cos(z) / z	tan(z) / z

scipy.special.gamma	scipy.special.digamma	mpmath.zeta

mpmath.siegeltheta	mpmath.siegelz	Riemann-Xi

Testing

To run the cplot unit tests, check out this repository and run

tox

Similar projects and further reading

• https://github.com/endolith/complex_colormap
• John D. Cook
• Elias Wegert, Visual Complex Functions
• Juan Carlos Ponce Campuzano, DC gallery