Skip to content

Plot f(x) = x^(1/5)

10 messages · Steven Stoline, Mark Daniel Ward, jim holtman +3 more

Original
Steven Stoline
# 
Dear All:


I am trying to plot the function f(x) = x^(1/5) for x=seq(-2,2,0.01). It
give me only the plot of f(x) for the positive part of x. I checked the
values of f(x), it is NaN for all negative values of x.

*this is my code:*


x<-seq(-2,2,0.01)
y<- (x)^(1/5)
plot(x,y, type="l", lwd=3, xlab = " ", ylab = " ", col="blue")
abline(v=0, col="gray", lty=2, lwd=3)
abline(h=0, col="gray", lty=2, lwd=3)



any help will be appreciated.


with many thanks
steve
Mark Daniel Ward
# 
Dear Steven,

Well, the values x^(1/5) are complex-valued (not real-valued) when x is 
negative.

Did you want to plot the absolute value of x^(1/5) instead?

Mark

Mark Daniel Ward, Ph.D.
Associate Professor and Undergraduate Chair
Department of Statistics
Purdue University
150 North University Street
West Lafayette, IN 47907-2067
mdw at purdue.edu
phone: (765) 496-9563
On 5/17/16 8:44 AM, Steven Stoline wrote:
jim holtman
# 
System is working correctly.  A negative number cannot be raised to a
fractional power:
[1] NaN




Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.
On Tue, May 17, 2016 at 8:44 AM, Steven Stoline <sstoline at gmail.com> wrote:

            

      
      
      
    

        

      
      
    

        

  
  


  


      

    

    

      
      

        


  

        

      Steven Stoline
    

    

      
      #
    

  


  

      
Dear All:

in my TI-Calculator (-0.5)^(1/5) = -0.8705, but in R  (-0.5)^(1/5) = NaN.


with thanks
steve

        
On Tue, May 17, 2016 at 8:52 AM, jim holtman <jholtman at gmail.com> wrote:

        

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Gabor Grothendieck
    

    

      
      #
    

  


  

      
Try this:

 y <- sign(x) * abs(x)^(1/5)

        
On Tue, May 17, 2016 at 8:44 AM, Steven Stoline <sstoline at gmail.com> wrote:

            

      
      
      
    

        

      
      
    

        

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      David Pell
    

    

      
      #
    

  


  

      
Try :

-0.5^(1/5)
[1] -0.8705506

David

-----Original Message-----
From: R-sig-teaching [mailto:r-sig-teaching-bounces at r-project.org] On Behalf Of Steven Stoline
Sent: 17 May 2016 14:07
To: jim holtman <jholtman at gmail.com>
Cc: R-sig-teaching <r-sig-teaching at r-project.org>
Subject: Re: [R-sig-teaching] Plot f(x) = x^(1/5)

Dear All:

in my TI-Calculator (-0.5)^(1/5) = -0.8705, but in R  (-0.5)^(1/5) = NaN.


with thanks
steve

        
On Tue, May 17, 2016 at 8:52 AM, jim holtman <jholtman at gmail.com> wrote:

        

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        
--
Steven M. Stoline
1123 Forest Avenue
Portland, ME 04112
sstoline at gmail.com


_______________________________________________
R-sig-teaching at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-sig-teaching

________________________________


This email may have a protective marking please see http://www.mrc.ac.uk/about/information-standards/document-marking-policy/ <http://www.mrc.ac.uk/about/information-standards/document-marking-policy/>

This email and any attachments are intended for the name...{{dropped:21}}

  
  


  


      

    

    

      
      

        


  

        

      Steven Stoline
    

    

      
      #
    

  


  

      
Dear Gabor:

many thanks,makes it.

steve

On Tue, May 17, 2016 at 9:07 AM, Gabor Grothendieck <ggrothendieck at gmail.com

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      jim holtman
    

    

      
      #
    

  


  

      
this is where you should be using parenthesis to make sure you have the
correct precedence of operations:

            

      
      
      
    

        
[1] -0.8705506

            

      
      
      
    

        
[1] NaN

            

      
      
      
    

        
[1] NaN

            

      
      
      
    

        
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.

On Tue, May 17, 2016 at 9:09 AM, David Pell <David.Pell at mrc-hnr.cam.ac.uk>
wrote:

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

  
  


  


      

    

    
1 day later

    

      
      

        


  

        

      Steven Stoline
    

    

      
      #
    

  


  

      
Dear All:


can someone please help me to plot the *Folium of Descrates:**  x^3+y^3=3xy
for x<-seq(-5,5,0.010) and **y<-seq(-5,5,0.010) *
<https://www.google.com/search?biw=1155&bih=597&q=R:+Folium+of+Descartes&spell=1&sa=X&ved=0ahUKEwiBrsnWpeTMAhUFKB4KHU5TD0EQvwUIGSgA>


with thanks
steve

On Tue, May 17, 2016 at 9:07 AM, Gabor Grothendieck <ggrothendieck at gmail.com

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      R. Michael Weylandt
    

    

      
      #
    

  


  

      
Use the t-parametrized form from e.g.,
http://mathworld.wolfram.com/FoliumofDescartes.html

t <- seq(-50, 50, by=0.01)
x <- 3*t/(1+t^3)
y <- 3*t^2/(1+t^3)
plot(x, y, xlim=c(-5, 5), ylim=c(-5, 5), type="l")

(I'm limiting the plot to avoid the huge values that occur near t=-1)

MW

        
On Wed, May 18, 2016 at 1:58 PM, Steven Stoline <sstoline at gmail.com> wrote: