如何 plot 一个 function 的 2 个变量

Question

I want to plot a function in R studio which has 2 variables: x1 and x2. This is what I have:

f_ejer1 <- function(x) {sqrt(144+x[1]^2) + sqrt(25+(x[2]-x[1])^2) + sqrt(4+(7-x[2])^2)}
x1_ejer1 <- seq(-1, 1, len=50)
x2_ejer1 <- seq(-1, 1, len=50)

z_ejer1 <- outer(x_ejer1,x2_ejer1, f_ejer1)

persp(x_ejer1, x2_ejer1,z_ejer1, theta=-30, phi=15, ticktype="detailed", col="lightblue", shade=0.2)

image(x_ejer1, x2_ejer1,z_ejer1)
contour(x_ejer1, x2_ejer1, z_ejer1, nlevels=15, col="black", add=T)

It shows this error: Error in FUN(X, Y, ...): unused argument (Y)

How can I fix it?

Answer 1

The following changes solve the problem.

1. Change the function to a function of two variables, since that's what outer will pass it.
2. Correct the typo, instead of x_ejer1 you have created x1_ejer1 .

And the code is almost the posted in the question.

f_ejer1 <- function(x, y) {
  sqrt(144 + x^2) + sqrt(25+(y - x)^2) + sqrt(4 + (7 - y)^2)
}

x1_ejer1 <- seq(-1, 1, len=50)
x2_ejer1 <- seq(-1, 1, len=50)

z_ejer1 <- outer(x1_ejer1, x2_ejer1, f_ejer1)

persp(x1_ejer1, x2_ejer1,z_ejer1, theta=-30, phi=15, ticktype="detailed", col="lightblue", shade=0.2)

image(x1_ejer1, x2_ejer1,z_ejer1)
contour(x1_ejer1, x2_ejer1, z_ejer1, nlevels=15, col="black", add=T)