kicad/eeschema/sim/user_defined_signals_help.md

SPICE functions:

    sqrt(x)
    sin(x)
    cos(x)
    tan(x)
    sinh(x)
    cosh(x)
    tanh(x)
    asin(x)
    acos(x)
    atan(x)
    asinh(x)
    acosh(x)
    atanh(x)
    arctan(x)
    exp(x)
    ln(x)
    log(x)
    abs(x)
    nint(x)
    int(x)
    floor(x)
    ceil(x)
    pow(x, y)
    pwr(x, y)
    min(x, y)
    max(x, y)
    sgn(x)
    ternary_fcn(x, y, z)
    gauss(nom, rvar, sigma)
    agauss(nom, avar, sigma)
    unif(nom, rvar)
    aunif(nom, avar)
    limit(nom, avar)