Strange behavior: random and plot
- To: mathgroup at smc.vnet.net
- Subject: [mg102726] Strange behavior: random and plot
- From: Don Krug <krugd at nku.edu>
- Date: Sat, 22 Aug 2009 03:36:55 -0400 (EDT)
Hi group. I am new here and discovered some strange behavior (to me.)
Hope someone can help.
I will be teaching a course on programming with Mathematica this
semester and so you may hear from me some more.
I define
ran[x_]:=Random[Real,x]
If I evaluate ran[3]-ran[3] I get a non-zero result as expected.
But if I do
Plot[ ran[x]-ran[x] ,{x,0,3}]
I get an empty axes system. I assume it is the plot of the zero function.
I also know that if I set
ran2[x_]:=Random[Real,x]
then I get a non-zero plot as expected when I do
Plot[ ran2[x]-ran[x] ,{x,0,3}]
I am guessing the plot command is evaluating things in a strange way
that forces the two instances of ran to be the same.
Can anyone explain why?
Thanks
Don Krug
Northern Kentucky U