To upload the package, just type:
library(matlib)
EXAMPLE 1: Recall we have the following system of linear equations such that x1 + x2 = 4 2x1 + x2 = 5. Its augmented matrix is 1 1 4 2 1 5 . In R you type:
A <- matrix(c(1,2,1,1), nrow = 2, ncol = 2)
If you type A, then R will return
A
## [,1] [,2]
## [1,] 1 1
## [2,] 2 1
Now we create a vector for the right-hand side of the system of linear equations:
b <- c(4, 5)
b
## [1] 4 5
Then, in order to solve the system of linear equations with the matlib package, just type:
Solve(A, b)
## x1 = 1
## x2 = 3
Without this package, if you failed to install matlib, just type
solve(A, b)
## [1] 1 3
EXAMPLE 2:
A <- matrix(c(1,-2,-1,2,3,2,3,-2,1), nrow = 3, ncol = 3)
A
## [,1] [,2] [,3]
## [1,] 1 2 3
## [2,] -2 3 -2
## [3,] -1 2 1
b <- c(6, -1, 2)
b
## [1] 6 -1 2
Solve(A, b)
## x1 = 1
## x2 = 1
## x3 = 1
Again, this package can plot not only the dimensional geometry but also it can plot the three-dimensional geometry of the system of linear equations. If you type as follows:
plotEqn3d(A,b, xlim=c(0,4), ylim=c(0,4))
EXAMPLE 3: In R, first you create the coefficient matrix A by the following:
A <- matrix(c(1,0,1,0,1,0,0,1,0,1,1,0,0,1,0,1),nrow=4,ncol=4)
A
## [,1] [,2] [,3] [,4]
## [1,] 1 1 0 0
## [2,] 0 0 1 1
## [3,] 1 0 1 0
## [4,] 0 1 0 1
Now we create a vector for the right-hand side of the system of linear equations such that
b <- c(475, 489, 542,422)
b
## [1] 475 489 542 422
Solve(A, b)
## x1 - 1*x4 = 53
## x2 + x4 = 422
## x3 + x4 = 489
## 0 = 0