TheAlgorithms/Python · error · ValueError

area_rhombus() only accepts non-negative values

Error message

area_rhombus() only accepts non-negative values

What it means

area_rhombus() raises this ValueError when diagonal_1 or diagonal_2 is negative. Diagonals are physical lengths; the library requires both >= 0 before returning 1/2 * d1 * d2. As with other product-based formulas, the guard prevents two negative inputs from silently yielding a positive, meaningless area.

Source

Thrown at maths/area.py:509

    >>> area_rhombus(1.6, 2.6)
    2.08
    >>> area_rhombus(0, 0)
    0.0
    >>> area_rhombus(-1, -2)
    Traceback (most recent call last):
        ...
    ValueError: area_rhombus() only accepts non-negative values
    >>> area_rhombus(1, -2)
    Traceback (most recent call last):
        ...
    ValueError: area_rhombus() only accepts non-negative values
    >>> area_rhombus(-1, 2)
    Traceback (most recent call last):
        ...
    ValueError: area_rhombus() only accepts non-negative values
    """
    if diagonal_1 < 0 or diagonal_2 < 0:
        raise ValueError("area_rhombus() only accepts non-negative values")
    return 1 / 2 * diagonal_1 * diagonal_2


def area_reg_polygon(sides: int, length: float) -> float:
    """
    Calculate the area of a regular polygon.
    Wikipedia reference: https://en.wikipedia.org/wiki/Polygon#Regular_polygons
    Formula: (n*s^2*cot(pi/n))/4

    >>> area_reg_polygon(3, 10)
    43.301270189221945
    >>> area_reg_polygon(4, 10)
    100.00000000000001
    >>> area_reg_polygon(0, 0)
    Traceback (most recent call last):
        ...
    ValueError: area_reg_polygon() only accepts integers greater than or equal to \
three as number of sides

View on GitHub (pinned to f5988cc097)

Solutions

1. Check both diagonals >= 0 before the call; correct the sign at the data source.
2. Convert signed spans to magnitudes with abs().
3. Validate imported geometry data before processing.
4. Catch ValueError for application-level error reporting.

Example fix

// before
area = area_rhombus(d1, d2)  # d1 = x2 - x1 may be negative

# after
area = area_rhombus(abs(x2 - x1), abs(y2 - y1))

if diagonal_1 < 0 or diagonal_2 < 0:
    raise ValueError(f'rhombus diagonals must be >= 0: {diagonal_1}, {diagonal_2}')
area = area_rhombus(diagonal_1, diagonal_2)

def is_valid_diagonals(d1: float, d2: float) -> bool:
    return d1 >= 0 and d2 >= 0

try:
    area = area_rhombus(diagonal_1, diagonal_2)
except ValueError as e:
    raise ValueError(f'invalid rhombus input: {e}') from e

When it happens

Trigger: Calling area_rhombus(diagonal_1, diagonal_2) with either argument < 0, e.g. area_rhombus(-1, 2) or area_rhombus(1, -2).

Common situations: Diagonals measured as coordinate spans with signed direction; drafting/CAD exports with sign conventions; missing-data sentinels.

Related errors

• surface_area_cube() only accepts non-negative values
• surface_area_cuboid() only accepts non-negative values
• surface_area_sphere() only accepts non-negative values
• surface_area_hemisphere() only accepts non-negative values
• surface_area_cone() only accepts non-negative values

AI-assisted analysis of TheAlgorithms/Python@f5988cc097 (2026-08-14). Data as JSON: /api/errors/38c815f5566c3509. Report an issue: GitHub.