TheAlgorithms/Python · error · ValueError

Area cannot be negative

Error message

Area cannot be negative

What it means

Raised by physics/shear_stress.py:shear_stress when the caller passes a negative value for the area argument. shear_stress solves for one of stress, tangential_force, or area from the other two, and a negative area is physically meaningless (it would flip the sign of the computed stress), so the function refuses it before doing any arithmetic. It is one of three per-argument sign checks that run after the 'exactly two of three inputs must be non-zero' check.

Source

Thrown at physics/shear_stress.py:38

    2. Tangential Force
    3. Cross-sectional Area
    This is calculated from the other two provided values
    Examples -
    >>> shear_stress(stress=25, tangential_force=100, area=0)
    ('area', 4.0)
    >>> shear_stress(stress=0, tangential_force=1600, area=200)
    ('stress', 8.0)
    >>> shear_stress(stress=1000, tangential_force=0, area=1200)
    ('tangential_force', 1200000)
    """
    if (stress, tangential_force, area).count(0) != 1:
        raise ValueError("You cannot supply more or less than 2 values")
    elif stress < 0:
        raise ValueError("Stress cannot be negative")
    elif tangential_force < 0:
        raise ValueError("Tangential Force cannot be negative")
    elif area < 0:
        raise ValueError("Area cannot be negative")
    elif stress == 0:
        return (
            "stress",
            tangential_force / area,
        )
    elif tangential_force == 0:
        return (
            "tangential_force",
            stress * area,
        )
    else:
        return (
            "area",
            tangential_force / stress,
        )


if __name__ == "__main__":

View on GitHub (pinned to f5988cc097)

Solutions

1. Pass a non-negative area; area must be > 0 when it is the unknown being solved for.
2. Check argument order against the signature shear_stress(stress, tangential_force, area) - magnitudes differ by orders of magnitude so a swap is usually visible.
3. If area is derived, clamp or validate the geometry inputs so the computed area cannot go negative.
4. Wrap the call in try/except ValueError if negative intermediates are possible in your pipeline and you want to reject the sample explicitly.

Example fix

# before
shear_stress(stress=0, tangential_force=1600, area=-200)

# after
shear_stress(stress=0, tangential_force=1600, area=200)

if area < 0:
    raise ValueError(f'area must be >= 0, got {area}')
result = shear_stress(stress=s, tangential_force=f, area=area)

def is_valid_shear_input(stress, tangential_force, area) -> bool:
    return (stress, tangential_force, area).count(0) == 1 and min(stress, tangential_force, area) >= 0

try:
    shear_stress(stress=s, tangential_force=f, area=a)
except ValueError as e:
    if 'Area' in str(e):
        # handle bad area specifically
        ...

When it happens

Trigger: Calling shear_stress with area < 0, e.g. shear_stress(stress=1000, tangential_force=500, area=-200) or shear_stress(stress=0, tangential_force=1600, area=-200). Note the check fires only when exactly one of the three arguments is 0; otherwise the 'more or less than 2 values' ValueError fires first.

Common situations: Swapping argument order so a force value lands in the area slot; computing area as a difference (a-b) that goes negative for degenerate geometry; porting unit conversions (cm^2 to m^2) that introduce a sign error; passing sentinel values like -1 for 'unknown'.

Related errors

• Gravitational force can not be negative
• Distance can not be negative
• Mass can not be negative
• Orbital radii must be greater than zero.
• The length should be non-negative

AI-assisted analysis of TheAlgorithms/Python@f5988cc097 (2026-08-14). Data as JSON: /api/errors/d6e4abc3c639331c. Report an issue: GitHub.