照度変換ツール

# Illuminance unit conversion in Python
# Conversion factors relative to lux (lx)
ILLUM_TO_LUX = {
    "lux":         1.0,
    "foot_candle": 10.7639,   # 1 fc = 10.7639 lux
    "phot":        10000.0,   # CGS unit: 1 ph = 10000 lux
    "nox":         0.001,     # 1 nox = 0.001 lux
}

def convert_illuminance(value: float, from_unit: str, to_unit: str) -> float:
    lux = value * ILLUM_TO_LUX[from_unit]
    return lux / ILLUM_TO_LUX[to_unit]

# Core formula: fc ↔ lux
def lux_to_fc(lux: float) -> float:
    return lux / 10.7639

def fc_to_lux(fc: float) -> float:
    return fc * 10.7639

# Examples
print(lux_to_fc(500))             # 46.45  (office 500 lux → fc)
print(fc_to_lux(50))              # 538.2  (stage lighting)
print(convert_illuminance(1000, "lux", "foot_candle"))  # 92.9
print(convert_illuminance(100,  "foot_candle", "lux"))  # 1076.39