Re: Differentiation and Polynomial questions
- To: mathgroup at smc.vnet.net
- Subject: [mg20764] Re: Differentiation and Polynomial questions
- From: David Pearson <david.pearson at mail.nerc-essc.ac.uk>
- Date: Thu, 11 Nov 1999 00:22:42 -0500
- Organization: ESSC
- References: <805vjq$ddu@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
Danny Mathews wrote:
> My Calculus instructor loves piece-wise functions. Any info on plotting
> them would be helpful.
An easy way is to plot all the pieces seperately, then show
them all at once with Show, like this:
In[7]:= Plot[Sin[x],{x,1,2}]
# # # # # # # # # # # # # # # # # # #
# #
###########################################################################
# 1.2 1##### 1.6 #### 1.8
2
# #### ####
0.975# ### ###
# ### ###
# ### ###
# ## ###
0.95 # ### ##
# ### ###
# ## ##
0.925# ## ###
# ###
##
# ##
##
# ##
0.9 # ##
# ##
# ##
0.875# ##
# ##
# ##
###
0.85 ##
#
Out[7]= -Graphics-
In[8]:= Plot[Cos[x],{x,2,3}]
#
##
####
# ###
# ###
-0.5# ###
# ####
# ###
# ###
-0.6# ####
# ###
# ####
-0.7# ###
# ####
# ####
# ####
-0.8# ####
# ####
# #####
# #####
-0.9# #####
# #######
# #######
# # # # # # # # # # # # # # # # # # ########
############################################################################
2.2 2.4 2.6 2.8
3
Out[8]= -Graphics-
In[9]:= Show[%,%%]
# ###########
1# ############ ############
#####
#
#
#
0.5#
#
#
#
#
# # # # # # # # # # # # # # # # # # #
# #
############################################################################
# 1.5 2 2.5
3
#
#
# ##
# ####
-0.5# #####
# ######
# ######
# #######
# ###########
-1#
###
Out[9]= -Graphics-
If you want to join the segments with vertical lines, use the UnitStep
function, whicc is zero for x<0, otherwise 1. You probably have to load
it through the DiracDelta package, i.e. type
<Calculus`DiracDelta`
Then you can plot a section of a function between 2 and 4.5 (for example)
by plotting (UnitStep[x-2] - UnitStep[x-4.5]) * f[x] , which includes
vertical lines at the ends of the section of the function. If you
plotted
(UnitStep[x-2]-UnitStep[x-4.5])*f[x]+(UnitStep[x-4.5]-UnitStep[x-7])*g[x]
you would get a segment of f[x] and one of g[x], joined with a vertical
line.
-David.
--
David Pearson, Phone: +44 (0)118 9318741
ESSC, Fax: +44 (0)118 9316413
University of Reading, Email: dwcp at mail.nerc-essc.ac.uk
Reading RG6 6AL,
UK. www.nerc-essc.ac.uk/~dwcp/Home.html