Ruby实现t分布

Question

I'm trying to find a ruby implementation of the t-distribution so I can draw a graph with a certain mean, standard deviation and degrees of freedom. Not totally sure if that makes sense, any help would be much appreciated.

Answer 1

I have to second DGM's comments about using R and Rinruby. Rinruby is fantastic because you can type R commands right into ruby :) You just need to make sure you have R installed on your system before you use it. If you want to see a T-Distribution in action (after installing R and the Rinruby gem) just the paste the following into irb:

require 'rinruby'

R.eval <<EOF
x <- seq(-4, 4, length=100)
hx <- dnorm(x)

degf <- c(1, 3, 8, 30)
colors <- c("red", "blue", "darkgreen", "gold", "black")
labels <- c("df=1", "df=3", "df=8", "df=30", "normal")

plot(x, hx, type="l", lty=2, xlab="x value",
  ylab="Density", main="Comparison of t Distributions")

for (i in 1:4){
  lines(x, dt(x,degf[i]), lwd=2, col=colors[i])
}

legend("topright", inset=.05, title="Distributions",
  labels, lwd=2, lty=c(1, 1, 1, 1, 2), col=colors)
EOF

Hope this helps you get started. I should note that I haven't needed to do a t-distribution recently so I shamelessly stole the R code from some R documentation.