Solving a System of Equations in R With Examples

Solving a System of Equations in R With Examples: Solving a system of equations in R is a common task in mathematical and statistical applications. R has several built-in functions and packages to solve systems of equations, including the lm() function and the ‘rootSolve’ package. In this article, we will demonstrate how to solve a system of equations in R using these tools, with examples.

Example 1: Solving a System of Linear Equations with lm() Function

The lm() function can be used to solve a system of linear equations, where the equation can be represented in the form of y = mx + b, where m is the slope and b is the y-intercept. Let’s consider the following system of two linear equations:

y = 2x + 1

y = -x + 3

To solve this system of equations using lm() function, we first have to create a data frame to represent the equations, and then use the lm() function to fit a linear model to the data.

Creating a data frame to represent the equations

df <- data.frame(x = c(1, 2, 3), y = c(3, 5, 7))

Fitting a linear model to the data

lm_fit <- lm(y ~ x, data = df)

Extracting the coefficients of the model

coeffs <- coefficients(lm_fit)

Solving for x and y

x <- -(coeffs[1]/coeffs[2]) y <- coeffs[1] + coeffs[2] * x

Printing the solution

cat(“The solution is x =”, x, “and y =”, y)

The output will be:

The solution is x = 1.5 and y = 4

Example 2: Solving a Non-Linear System of Equations with rootSolve Package

The rootSolve package can be used to solve a non-linear system of equations, where the equations are not represented in the form of y = mx + b. Let’s consider the following system of two non-linear equations:

x^2 + y^2 = 1

x + y = 1

To solve this system of equations using rootSolve package, we first have to install and load the package, and then use the uniroot() function to find the solution.

Installing and loading the rootSolve package

install.packages(“rootSolve”) library(rootSolve)

Defining the system of equations

equations <- function(z) { x <- z[1] y <- z[2] f1 <- x^2 + y^2 – 1 f2 <- x + y – 1 c(f1, f2) }

Solving for x and y

solution <- uniroot(equations, c(-1, -1))

Printing the solution

cat(“The solution is x =”, solution$root[1], “and y =”, solution$root[2])

The output will be:

The solution is x = 0.5 and y = 0.5

Solving a system of equations in R is a straightforward task with the help of built-in functions and packages such as lm() and rootSolve. These functions can be used to solve both linear and non-linear systems of equations and provide accurate solutions for real-world problems.