Extract: Extract or replace parts of three-velocity

In RobinHankin/gyrogroup: The Lorentz Transform in Relativistic Physics

Extract or replace parts of three-velocity

Description

Extract or replace subsets of three-velocities

Arguments

x	A three-vector
index	elements to extract or replace
value	replacement value

Details

These methods (should) work as expected: an object of class 3vel is a three-column matrix with rows corresponding to three-velocities; a single argument is interpreted as a row number. Salient use-cases are u[1:5] <- u[1] and u[1] <- 0.

To extract a single component, pass a second index: u[,1] returns the x- component of the three-velocity.

Extraction functions take a drop argument, except for x[i] which returns a vec object.

Currently, u[] returns u but I am not sure this is desirable. Maybe it should return unclass(u) or perhaps c(unclass(u)).

Use idiom u[] <- x to replace entries of u elementwise.

Examples

u <- r3vel(10)
u[1:4]
u[5:6] <- 0

u[7:8] <- u[1]

u[,1] <- 0.1

RobinHankin/gyrogroup documentation built on April 24, 2024, 9:36 a.m.