lfit:functions

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Built-in operators

(.)+(.)
addition
(.)-(.)
subtraction
-(.)
negation
(.)*(.)
multiplication
(.)/(.)
division
(.)^(.)
power (right-associative)

Built-in elementary functions

sin(.)
sine function (argument in radians)
cos(.)
cosine function (argument in radians)
tan(.)
tangent function (argument in radians)
cot(.)
cotangent function (argument in radians)
asin(.)
inverse sine function (results radians)
acos(.)
inverse cosine function (results radians)
atan(.)
inverse tangent function (results radians)
acot(.)
inverse cotangent function (results radians)
exp(.)
exponential function (natural, e-based)
log(.)
natural logarithm
exp10(.)
exponential function (base 10)
log10(.)
logarithm to the base 10

Built-in functions

sqrt(.)
square root function
abs(.)
absolute value function
sign(.)
sign function
theta(.)
Heaviside step function
int(.)
integer part function (i.e. results the largest integer which is not larger than the argument)
div(.,.)
integer division, div(x,y) is equivalent to int(x/y)
mod(.,.)
real fractional remainder function
arg(.,.)
two dimensional argument function (results radians)
atan2(.,.)
two dimensional argument function, as defined in some programming languages, i.e. atan2(y,x)=arg(x,y) (results radians)
hypot(.,.)
hypotenuse function, it results the hypotenuse of a right triangle of which catheti are the two arguments of the function
pi()
results the value of \pi (a function with no arguments)

Built-in interpolation functions

ilinear(.,.,.)
base function of linear interpolation
ispline(.,.,.)
base function of cubic spline interpolation
icyspline(.,.)
base function of cyclic cubic spline interpolation

Built-in functions

jbessel(.,.)
Bessel function of the first kind
ybessel(.,.)
Bessel function of the second kind
ellipticK(.)
complete elliptic integral of the first kind
ellipticE(.)
complete elliptic integral of the second kind
ellipticPi(.,.)
complete elliptic integral of the third kind


Built-in functions related to orbital geometry and Keplerian motion

eoq(.,.,.)
eccentric offset function, `q` component (arguments: mean longitude in radians, k and h Lagrangian elements)
eop(.,.,.)
eccentric offset function, `p` component (arguments: mean longitude in radians, k and h Lagrangian elements)
etc(.,.,.)
eccentric trigonometric function, cosine component (arguments: mean longitude in radians, k and h Lagrangian elements)
ets(.,.,.)
eccentric trigonometric function, sine component (arguments: mean longitude in radians, k and h Lagrangian elements)

Built-in functions related to stellar occultations and transits

ntiu(.,.)
normalized transit intensity - uniform flux distribution (arguments: fractional radius, normalized distance)
ntiq(.,.,.,.)
normalized transit intensity - quadratic limb darkening assumption (arguments: fracional radius, normalized distance, the two limb darkening coefficients)

Built-in functions related to Julian Day calculations

hjd(.,.,.)
heliocentric Julian date (arguments: julian day, RA and DEC, in degrees)
bjd(.,.,.)
barycentric Julian date (arguments: julian day, RA and DEC, in degrees)
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