关于画PDF和CDF的一些问题

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t <- seq(from=-3,to=3,by=0.01)
plot(t,dnorm(t),ylab="PDF")
plot(t,pnorm(t),ylab="PDF")
这个是画简单的PDF和CDF图，现在又如下要求：
plotthe probability density function and cumulative distribution function(Prob(T)<t) for the t-distribution with infinity, 10 and 1 degree offreedom.Make the y-limit of the first and second figure rangefrom 0 to 0.5 and 0 to 1 respectively. Make sure the main title is in a fonttwice the default size, the y-axes are labeled as shown, and the line types 1,2and 3 correspond to the t-distribution with Inf, 10 and 1 degree of freedomrespectively.
标题和两个坐标轴有一些要求，这个较好实现，但是在一张图上实现3个不同的自由度的绘图，然后要怎么实现呢，效果图如下所示：
前辈们，在具体的函数中要用到哪些参数，能指教一下吗，谢谢

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关键词：cdf PDF

The basic idea is to use "lines" function to add pdf lines one by one, take "pdf" assignment for example:

1. pts <- seq(-3, 3, length = 1000)
   
2. plot(pts, dnorm(pts), type = "n", xlim = c(-3, 3), ylim = c(0, 0.5), main =
   
3. "PDF", xlab = "x", ylab = "f(x)")
   
4. lines(pts, dnorm(pts), lty = 1)
   
5. lines(pts, dt(pts, df = 10), lty = 2)
   
6. lines(pts, dt(pts, df = 1), lty = 3)
   
7. legend("topright", c(expression(paste("df = ", infinity)), "df = 10", "df = 1"), lty = 1:3)

复制代码

hugebear 发表于 2015-4-22 00:44
The basic idea is to use "lines" function to add pdf lines one by one, take "pdf" assignment for exa ...

谢谢哥们，昨天在网上查找的过程中，已经大概掌握了思路，就是卡在了自由度这里