This finds and returns a description of one or more dynamically loaded or ‘exported’ built-in native symbols. For each name, it returns information about the name of the symbol, the library in which it is located and, if available, the number of arguments it expects and by which interface it should be called (i.e .Call, .C, .Fortran, or .External). Additionally, it returns the address of the symbol and this can be passed to other C routines. Specifically, this provides a way to explicitly share symbols between different dynamically loaded package libraries. Also, it provides a way to query where symbols were resolved, and aids diagnosing strange behavior associated with dynamic resolution.
autoload
(Package: base) :
On-demand Loading of Packages
autoload creates a promise-to-evaluate autoloader and stores it with name name in .AutoloadEnv environment. When R attempts to evaluate name, autoloader is run, the package is loaded and name is re-evaluated in the new package's environment. The result is that R behaves as if file was loaded but it does not occupy memory.
A call to browser can provide context by supplying either a text argument or a condition argument. These functions can be used to retrieve either of these arguments.
save writes an external representation of R objects to the specified file. The objects can be read back from the file at a later date by using the function load or attach (or data in some cases).
chol2inv
(Package: base) :
Inverse from Choleski (or QR) Decomposition
Invert a symmetric, positive definite square matrix from its Choleski decomposition. Equivalently, compute (X'X)^(-1) from the (R part) of the QR decomposition of X.
providing 
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