a3ff46390b10c6069597ad8b98d0cbb77b48d8ef,scipy/constants/codata.py,,,#,1706

Before Change

exact_values = {
    "vacuum mag. permeability": (mu0, "N A^-2", 0.0),
    "vacuum electric permittivity": (epsilon0, "F m^-1", 0.0),
    "atomic unit of permittivity": (4 * epsilon0 * pi, "F m^-1", 0.0),
    "joule-kilogram relationship": (1 / (c * c), "kg", 0.0),
    "kilogram-joule relationship": (c * c, "J", 0.0),

After Change

    
c = value("speed of light in vacuum")
mu0 = value("vacuum mag. permeability")
epsilon0 = value("vacuum electric permittivity")

// Table is lacking some digits for exact values: calculate from definition
exact_values = {
    "joule-kilogram relationship": (1 / (c * c), "kg", 0.0),
    "kilogram-joule relationship": (c * c, "J", 0.0),
    "hertz-inverse meter relationship": (1 / c, "m^-1", 0.0),

    // The following derived quantities are no longer exact (CODATA2018):
    // specify separately
    "characteristic impedance of vacuum": (
        sqrt(mu0 / epsilon0), "ohm",
        sqrt(mu0 / epsilon0) * 0.5 * (
            physical_constants["vacuum mag. permeability"][2] / mu0
            + physical_constants["vacuum electric permittivity"][2] / epsilon0))
}

// sanity check
for key in exact_values:

Instances