daxpy {bigalgebra} | R Documentation |
This function implements the function Y := A * X + Y where X and Y may be either native double-precision valued R matrices or numeric vectors, or double-precision valued big.matrix
objects, and A is a scalar.
daxpy(A = 1, X, Y)
A |
Optional numeric scalar value to scale the matrix |
X |
Requried to be either a native R |
Y |
Optional native R |
At least one of either X
or Y
must be a big.matrix
. All values must be of type double
(the only type presently supported by the bigalgebra package).
This function is rarely necessary to use directly since the bigalgebra package defines standard arithmetic operations and scalar multiplication. It is more efficient to use daxpy
directly when both scaling and matrix addition are required, in which case both operations are performed in one step.
The output value depends on the classes of input values X
and Y
and on the value of the global option bigalgebra.mixed_arithmetic_returns_R_matrix
.
If X
and Y
are both big matrices, or Y
is missing, options("bigalgebra.mixed_arithmetic_returns_R_matrix")
is FALSE
, then a big.matrix
is returned. The returned big.matrix
is backed by a temporary file mapping that will be deleted when the returned result is garbage collected by R (see the examples).
Otherwise, a standard R matrix is returned. The dimensional shape of the output is taken from X
. If input X
is dimensionless (that is, lacks a dimension attribute), then the output is a column vector.
Michael J. Kane
https://www.netlib.org/blas/daxpy.f
require(bigmemory)
A = matrix(1, nrow=3, ncol=2)
B <- big.matrix(3, 2, type="double", init=0,
dimnames=list(NULL, c("alpha", "beta")), shared=FALSE)
C = B + B # C is a new big matrix
D = A + B # D defaults to a regular R matrix, to change this, set the option:
# options(bigalgebra.mixed_arithmetic_returns_R_matrix=FALSE)
E = daxpy(A=1.0, X=B, Y=B) # Same kind of result as C
print(C[])
print(D)
print(E[])
# The C and E big.matrix file backings will be deleted when garbage collected:
# (We enable debugging to see this explicitly)
options(bigalgebra.DEBUG=TRUE)
rm(C,E)
gc()