# plotEqn3d: Plot Linear Equations in 3D In matlib: Matrix Functions for Teaching and Learning Linear Algebra and Multivariate Statistics

## Description

Shows what matrices A, b look like as the system of linear equations, A x = b with three unknowns, x1, x2, and x3, by plotting a plane for each equation.

## Usage

 ```1 2 3``` ```plotEqn3d(A, b, vars, xlim = c(-2, 2), ylim = c(-2, 2), zlim, col = 2:(nrow(A) + 1), alpha = 1, labels = FALSE, solution = TRUE, axes = TRUE, lit = FALSE) ```

## Arguments

 `A` either the matrix of coefficients of a system of linear equations, or the matrix `cbind(A,b)` The `A` matrix must have three columns. `b` if supplied, the vector of constants on the right hand side of the equations, of length matching the number of rows of `A`. `vars` a numeric or character vector of names of the variables. If supplied, the length must be equal to the number of unknowns in the equations. The default is `paste0("x", 1:ncol(A)`. `xlim` axis limits for the first variable `ylim` axis limits for the second variable `zlim` horizontal axis limits for the second variable; if missing, `zlim` is calculated from the range of the set of equations over the `xlim` and `ylim` `col` scalar or vector of colors for the lines, recycled as necessary `alpha` transparency applied to each plane `labels` logical, or a vector of character labels for the equations; not yet implemented. `solution` logical; should the solution point for all equations be marked (if possible) `axes` logical; whether to frame the plot with coordinate axes `lit` logical, specifying if lighting calculation should take place on geometry; see `rgl.material`

## Value

nothing; used for the side effect of making a plot

## Author(s)

Michael Friendly, John Fox

## References

Fox, J. and Friendly, M. (2016). "Visualizing Simultaneous Linear Equations, Geometric Vectors, and Least-Squares Regression with the matlib Package for R". useR Conference, Stanford, CA, June 27 - June 30, 2016.

## Examples

 ```1 2 3 4``` ```# three consistent equations in three unknowns A <- matrix(c(13, -4, 2, -4, 11, -2, 2, -2, 8), 3,3) b <- c(1,2,4) plotEqn3d(A,b) ```

matlib documentation built on April 4, 2018, 5:03 p.m.