R help - Dec 2010 - Plotting own function

Hello,
I have a simple question but didn't find a solution.
How do I plot a custom function.

I have defined this function

func <- function(x) {
	y <- exp(-0.5*((x-63.9)/23.2)^2)
	if(x > 63.9)
		return(2 - y)
	else {
		return(y)
	}
}

and want to plot it in a specified range like

x = seq(-10,150,length=500)
y <- func(x)
plot(x,y,type="l",lwd=2,col="red")

But it doesn't work because it expects a vector but I need to compare the
scalar x.
How do I do it correctly?

Thanks a lot
Tobias

You need to use 'ifelse' in this case since it will handle a vector
and 'if' is only for single values:

func <- function(x) {
       y <- exp(-0.5*((x-63.9)/23.2)^2)
       ifelse(x > 63.9, 2 - y, y)
}


x = seq(-10,150,length=500)
y <- func(x)
plot(x,y,type="l",lwd=2,col="red")



On Tue, Dec 7, 2010 at 6:57 AM, Tobias Schultze <webmaster at
tubo-world.de> wrote:
> Hello,
> I have a simple question but didn't find a solution.
> How do I plot a custom function.
>
> I have defined this function
>
> func <- function(x) {
> ? ? ? ?y <- exp(-0.5*((x-63.9)/23.2)^2)
> ? ? ? ?if(x > 63.9)
> ? ? ? ? ? ? ? ?return(2 - y)
> ? ? ? ?else {
> ? ? ? ? ? ? ? ?return(y)
> ? ? ? ?}
> }
>
> and want to plot it in a specified range like
>
> x = seq(-10,150,length=500)
> y <- func(x)
> plot(x,y,type="l",lwd=2,col="red")
>
> But it doesn't work because it expects a vector but I need to compare
the
> scalar x.
> How do I do it correctly?
>
> Thanks a lot
> Tobias
>
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?