complex-range

Generate ranges of complex numbers - rectangular grids and linear sequences in the complex plane.

Python translation of the Mathematica resource function "ComplexRange".

Installation

pip install complex-range

Overview

complex_range generates ranges of complex numbers, extending Python's range functionality to the complex plane. It supports two modes:

• Rectangular ranges: Generate all points on a 2D grid spanning from minimum to maximum real and imaginary parts
• Linear ranges: Generate points along a line between two complex numbers

Step sizes can be specified as a complex number (e.g., 0.5+0.5j) or as separate real and imaginary steps in list form (e.g., [0.5, 0.5]). By default, the imaginary part is incremented first throughout its range with the real part fixed, then the real part is incremented—this behavior can be reversed via the increment_first option.

The farey_range option enables a complex generalization of the Farey sequence, creating mathematically refined point distributions in the complex plane.

Usage

Rectangular Ranges

Generate a grid of complex numbers between two corners:

Im ↑
 4 │  ·  ·  ·
 3 │  ·  ·  ·
 2 │  ·  ·  ·
 1 │  ·  ·  ·
   └──────────→ Re
      1  2  3

from complex_range import complex_range

# Basic rectangular range
complex_range(0, 2+2j)
# Returns: [0j, 1j, 2j, (1+0j), (1+1j), (1+2j), (2+0j), (2+1j), (2+2j)]

# Single argument: range from 0 to z
complex_range(2+3j)
# Returns grid from 0 to 2+3j (3×4 = 12 points)

# With custom step size (complex number)
complex_range(0, 2+2j, 0.5+0.5j)
# Real step = 0.5, Imaginary step = 0.5

# With separate real and imaginary steps
complex_range(0, 4+6j, [2, 3])
# Real step = 2, Imaginary step = 3

With increment_first='im' (default), points are generated column by column: (0,0), (0,1), (0,2), (0,3), (1,0), (1,1), ...

Linear Ranges

Generate points along a line (diagonal) in the complex plane:

Im ↑
 4 │        ·
 3 │     ·
 2 │  ·
 1 │·
   └──────────→ Re
     1  2  3

Points increment along both axes simultaneously.

# Linear from 0 to endpoint
complex_range([3+3j])
# Returns: [0j, (1+1j), (2+2j), (3+3j)]

# Linear between two points
complex_range([-1-1j, 2+2j])
# Returns: [(-1-1j), 0j, (1+1j), (2+2j)]

# Linear with custom step
complex_range([0, 4+4j], [2, 2])
# Returns: [0j, (2+2j), (4+4j)]

# Linear with complex step
complex_range([0, 4+4j], 2+2j)
# Returns: [0j, (2+2j), (4+4j)]

# Descending linear range with negative step
complex_range([2+2j, 0], -1-1j)
# Returns: [(2+2j), (1+1j), 0j]

Options

increment_first

Control the iteration order for rectangular ranges:

# Default: increment imaginary first
complex_range(0, 2+2j, 1+1j, increment_first='im')
# [0j, 1j, 2j, (1+0j), (1+1j), (1+2j), (2+0j), (2+1j), (2+2j)]

# Increment real first
complex_range(0, 2+2j, 1+1j, increment_first='re')
# [0j, (1+0j), (2+0j), 1j, (1+1j), (2+1j), 2j, (1+2j), (2+2j)]

farey_range

Use Farey sequence to create a finer subdivision of the grid:

# Regular grid
regular = complex_range(0, 4+4j, 2+2j)
# Returns 9 points

# Farey subdivision (step must be integer)
farey = complex_range(0, 4+4j, 2+2j, farey_range=True)
# Returns 81 points using Farey sequence F_2

# Farey sequence of order n creates fractions 0, 1/n, ..., 1
from complex_range import farey_sequence
farey_sequence(3)
# [Fraction(0,1), Fraction(1,3), Fraction(1,2), Fraction(2,3), Fraction(1,1)]

Applications

Mandelbrot Set Visualization

from complex_range import complex_range
import matplotlib.pyplot as plt
import numpy as np

def mandelbrot_escape(c, max_iter=100):
    z = 0
    for i in range(max_iter):
        z = z*z + c
        if abs(z) > 2:
            return i
    return max_iter

# Grid parameters
re_min, re_max = -2, 1
im_min, im_max = -1.5, 1.5
step = 0.005

# Generate grid and compute escape times
grid = complex_range(re_min + im_min*1j, re_max + im_max*1j, [step, step])
escapes = [mandelbrot_escape(c) for c in grid]

# Reshape and plot
n_re = int((re_max - re_min) / step) + 1
n_im = int((im_max - im_min) / step) + 1
escape_array = np.array(escapes).reshape(n_re, n_im).T

plt.figure(figsize=(10, 8))
plt.imshow(escape_array, extent=[re_min, re_max, im_min, im_max],
           origin='lower', cmap='hot', aspect='equal')
plt.colorbar(label='Escape iterations')
plt.xlabel('Real')
plt.ylabel('Imaginary')
plt.title('Mandelbrot Set')
plt.savefig('mandelbrot.png', dpi=150)
plt.show()

See Also

For more examples and details, see the documentation for the corresponding Wolfram Language "ComplexRange" resource function, contributed by the same author and vetted by the Wolfram Review Team.

License

This project is licensed under the MIT License - see the LICENSE file for details.