Power Density Converter

# Power density unit conversions
CONVERSIONS = {
    'W/m2':   1,
    'W/cm2':  10000,
    'mW/cm2': 10,
    'W/in2':  1550.0031,
    'kW/m2':  1000,
}

def convert_power_density(value: float, from_unit: str, to_unit: str) -> float:
    """Convert between power density units via W/m² base."""
    if from_unit not in CONVERSIONS or to_unit not in CONVERSIONS:
        raise ValueError(f"Unknown unit. Choose from: {list(CONVERSIONS.keys())}")
    return value * CONVERSIONS[from_unit] / CONVERSIONS[to_unit]

# Examples
print(f"1 kW/m² = {convert_power_density(1, 'kW/m2', 'W/m2')} W/m²")
print(f"1000 W/m² = {convert_power_density(1000, 'W/m2', 'mW/cm2')} mW/cm²")
print(f"Solar irradiance (1 kW/m²):")
for unit in CONVERSIONS:
    val = convert_power_density(1, 'kW/m2', unit)
    print(f"  {val:.6g} {unit}")