This modifies the names of the dimensions in a simple and reversible
way by adding a mark.
Usage
mark(X,mark,...)
## S3 method for class 'tensor'
mark(X,mark="'",i=1:level.tensor(X),...,by=NULL)
## S3 method for class 'numeric'
mark(X,mark="'",i=1:length(X),...,by=NULL)
## S3 method for class 'character'
mark(X,mark="'",i=1:length(X),...,by=NULL)
Arguments
X
A tensor or dimension to be marked
mark
a character giving the mark
i
the dimensions to be marked
...
generic arguments
by
Dimensions not to be marked. Wins in case of conflicts.
Details
The concept is very important in tensor algebra since it allows to
keep dimensions connected without but still
distinguishable. Eventually later a function for the Riemann summing
rule will make use of marks to distinguish covariate and contravariate
dimensions.
Value
A object similar to X but with marked dimensions.
Author(s)
K. Gerald van den Boogaart
See Also
delta.tensor, diag.tensor
Examples
# The outer product
A <- to.tensor(1:4,c(a=2,b=2))
A