How to compare trigonometric functions in R?-CodePudding

How can I show that these 2 functions are equal?

a<-function(x) sec^2(x)
b<-function(x) 1 tan^2(x)

I tried using identical but it’s showing false.

identical(a,b)
[1] FALSE

CodePudding user response：

Using just base R, you can take some range of values for x, compute values for these values for both functions and see if they are equal.

a <- function(x) (1/cos(x))^2

b <- function(x) 1   tan(x)^2

x <- seq(from = -2 * pi, to = 2*pi, length.out = 1e4)

all.equal(a(x), b(x))
# TRUE

CodePudding user response：

In case you have Maxima installed (that is free), you can use rim:

library(rim)
#> Maxima successfully registered as knitr engine!

maxima.get("trigsimp(1 (tan(x))^2 - (sec(x))^2);")
#> (%o1) 0