# Ginv

0th

Percentile

##### Generalized Inverse of a Matrix

Ginv returns an arbitrary generalized inverse of the matrix A, using gaussianElimination.

##### Usage
Ginv(A, tol = sqrt(.Machine\$double.eps), verbose = FALSE,
fractions = FALSE)
##### Arguments
A

numerical matrix

tol

tolerance for checking for 0 pivot

verbose

logical; if TRUE, print intermediate steps

fractions

logical; if TRUE, try to express non-integers as rational numbers

##### Details

A generalized inverse is a matrix $$\mathbf{A}^-$$ satisfying $$\mathbf{A A^- A} = \mathbf{A}$$.

The purpose of this function is mainly to show how the generalized inverse can be computed using Gaussian elimination.

##### Value

the generalized inverse of A, expressed as fractions if fractions=TRUE, or rounded

ginv for a more generally usable function

• Ginv
##### Examples
# NOT RUN {
A <- matrix(c(1,2,3,4,5,6,7,8,10), 3, 3) # a nonsingular matrix
A
Ginv(A, fractions=TRUE)  # a generalized inverse of A = inverse of A
round(Ginv(A) %*% A, 6)  # check

B <- matrix(1:9, 3, 3) # a singular matrix
B
Ginv(B, fractions=TRUE)  # a generalized inverse of B
B %*% Ginv(B) %*% B   # check

# }

Documentation reproduced from package matlib, version 0.9.2, License: GPL (>= 2)

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