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## Drawing Normal Graphs - Shading not consistent

 From: Albert Kinderman Subject: Drawing Normal Graphs - Shading not consistent Date: Mon, 07 Apr 2003 08:45:53 -0700 User-agent: Mozilla/5.0 (X11; U; Linux i386; en-US; rv:0.9.4.1) Gecko/20020508 Netscape6/6.2.3

```Hi:

```
I teach statistics and find it useful to draw graphs of the normal distribution with certain areas filled in (shaded). I have tried to create a def that will produce the shaded graph. What follows is my mydefs file and a sample document.
```
```
The problem is that sometimes the shading goes all the way to the upper limit and sometimes it stops short. Note, because I step through the graph by .1, both the lower and upper arguments should be rounded to the nearest .1.
```
Does anyone have any suggestions?

[file mydefs]

import @Graph @Data

def @NormalDensity
right x
{ {1/{sqrt 2*pi}}*e exp {-.5*x*x}}

def @NormalFilledGraph left low right high
{ @Graph
style { axes }
belowgap {0}
xorigin {0}
yorigin {0}
xmin {-2.5}
xmax {2.5}
ymin {0}
xticks {}
yticks {}
yextra {0}
height {2 cm}
{
@Data   pairs {solid}
paint {yes}
color {lightgrey}
{xloop from {low} to {high} by {.1} do
{x @NormalDensity x}}
@Data   pairs {solid}
{xloop from {-2.5} to {2.5} by {.1} do
{x @NormalDensity x}}
@Data   pairs {solid}
{low 0 low  @NormalDensity low}
@Data   pairs {solid}
{high 0 high @NormalDensity high}
```
}
```}

[sample document]

@SysInclude { graph }
@SysInclude { doc }

@Doc
@Text
@Begin
@CD   .6 @NormalFilledGraph 1.4

@CD -2.5 @NormalFilledGraph .3

@CD   .3 @NormalFilledGraph .7

@CD  -.6 @NormalFilledGraph .5

@End
@Text

```