misc: Miscellaneous helper functions

In RobinHankin/schwarzschild: General Relativity in R

Miscellaneous helper functions

Description

Various helper functions that should not appear in the plotting routines

Usage

RT(TX)
TX(rt,exterior)
cone(x, y, leftangle, rightangle, size = 0.2, colours=standard_colours, ...)
lightcone(x, y, size, colours = standard_colours) 
raindrop(r)  
ingoing(r,rzero,tzero=0)
outgoing(r,rzero,tzero=0)
ingoing_lambert(t,rzero,tzero=0)
outgoing_lambert(t,rzero,tzero=0)
shifter(x,w=1)

Arguments

TX, rt	Two-column matrix giving time and space
exterior	Boolean, specifying whether the point in question is inside or outside the event horizon
x, y, leftangle, rightangle, size, colours, ...	Arguments for cone() and lightcone() specifying features of a light cone
r, t	Schwarzschild radius and Schwarzschild time
rzero, tzero	In functions ingoing() and outgoing(), arguments tzero and rzero specify an event through which the null geodesic passes
w	Amount to shift horizontally

Details

• Function lightcone() plots a nice little light cone on a plot. It is more user-friendly than the lower-level function cone().

• Functions raindrop() and raindrop_arrow() are used in schwarzschild() to draw worldlines of particles falling from rest at infinity. Note that functions gullstrand() and lemaitre() have options to plot raindrops but use unrelated internal code to do so.

• Functions ingoing() and outgoing() give the ingoing or outgoing light curve passing through event (rzero,tzero). They take (Schwarzschild) radial coordinate r and return (Schwarzschild) time t. Note that, in Schwarzschild coordinates, radial null geodesics are either always inside, or always outside, r=1 (this applies to both ingoing and outgoing light).

  These functions return t as a function of r. Functions ingoing_lambert() and outgoing_lambert() use Lambert W function (of the gsl package) to take t and return r

Author(s)

Robin K. S. Hankin

RobinHankin/schwarzschild documentation built on Nov. 13, 2024, 12:58 p.m.