R Language: Drawing Function Plots (Part I - Basic Curves)

Besides the fact that is free, one of the advantages of the R language is that it allows drawing function plots with simple commands. All one needs is software package like Microsoft R Open and one is set to go.

For example, to draw the function f(x) = x^3-3*x+2 all one needs to do is to type the following command into the console:

curve(x^3-3*x+2, -3,3)

One can display a second function into the same chart by adding a second command and repeat the process further as needed:

curve(x^2-3*x+2, add=TRUE, col="blue")
curve(x^4-3*x+2, add=TRUE, col="red")
curve(x^5-3*x+2, add=TRUE, col="green")

As one can see a pattern emerges already …

One could easily display the plots in their one section by defining an array on the display device, allowing thus to focus on special characteristics of the functions:

par(mfrow=c(2,2))
curve(x^3-3*x+2, -3,3)
curve(x^2-3*x+2, -3,3, col="blue")
curve(x^4-3*x+2, -3,3, col="red")
curve(x^5-3*x+2, -3,3, col="green")

One can be creative and display the functions using a loop:

par(mfrow=c(2,2))
for(n in c(2:5)){
curve(x^n-3*x+2, -3,3)
}

Similarly, one can plot trigonometric functions:

par(mfrow=c(2,3))
curve(sin(x),-pi,pi) 
curve(cos(x),-pi,pi) 
curve(tan(x),-pi,pi) 
curve(1/tan(x),-pi,pi) 
curve(asin(x),-1,1)
curve(acos(x),-1,1)

The possibilities are endless. For complex functions one can include the function into an r function:

myFunction<- function(x) sin(cos(x)*exp(-x/2))
curve(myFunction, -15, 15, n=1000)

For the SQL Server developers, what’s even greater is the possibility of using Management Studio for the same, though that’s a topic for another post.

 

Happy coding!

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