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Re: Routines inside Epilog

  • To: mathgroup at smc.vnet.net
  • Subject: [mg14395] Re: Routines inside Epilog
  • From: "P.J. Hinton" <paulh>
  • Date: Sun, 18 Oct 1998 15:10:01 -0400
  • Organization: "Wolfram Research, Inc."
  • References: <7040at$i3i@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

On 15 Oct 1998, GERMAN BUITRAGO wrote:

> I need to plot many lines between a curve and the x-axis for to show an
>  approximation of the area under the curve. 
>  
> Example:  
> f[x_] := 36 - 4*(x - 3)^2
> 
> Plot[f[x], {x, 0, 3}]
> 
> Plot[f[x], {x, 0, 3}, Epilog -> {Line[{ {0.2, 0}, {0.2, f[0.2]}, {0.4,f[0.2]} }], 
> Line[{ {0.4, 0},{0.4, f[0.4]},{0.6, f[0.4]}}]]
> 
> All the above-mentioned works correctly. However, I am not able to 
> create a routine for several similar lines, as:
> 
> Plot[f[x], {x, 0, 3}, Epilog -> Do[Line[{ {i, 0}, {i, f[i]}, {i+.2, f[i]} }],
> {i,15} ]]
> 
> Where is my error?   

Epilog should be a list of graphics primitives, but Do[] returns a Null
result. Try using Table[] instead.

Plot[f[x], {x, 0, 3}, 
  Epilog -> Table[Line[{ {i, 0}, {i, f[i]}, {i+.2, f[i]} }], {i,15} ]]

--
P.J. Hinton
Mathematica Programming Group           paulh at wolfram.com Wolfram
Research, Inc.                  http://www.wolfram.com/~paulh/
Disclaimer: Opinions expressed herein are those of the author alone.



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