## 1.9.4 Advanced Topic: Manipulating Options

There are a number of functions built into Mathematica which, like Plot, have various options you can set. Mathematica provides some general mechanisms for handling such options.

If you do not give a specific setting for an option to a function like Plot, then Mathematica will automatically use a default value for the option. The function Options[function, option] allows you to find out the default value for a particular option. You can reset the default using SetOptions[function, option->value]. Note that if you do this, the default value you have given will stay until you explicitly change it.

 Options[function] give a list of the current default settings for all options Options[function, option] give the default setting for a particular option SetOptions[function, option->value, ... ] reset defaults

Manipulating default settings for options.
Here is the default setting for the PlotRange option of Plot.
 In[1]:=  Options[Plot, PlotRange]
 Out[1]=
This resets the default for the PlotRange option. The semicolon stops Mathematica from printing out the rather long list of options for Plot.
 In[2]:=  SetOptions[Plot, PlotRange->All] ;
Until you explicitly reset it, the default for the PlotRange option will now be All.
 In[3]:=  Options[Plot, PlotRange]
 Out[3]=

The graphics objects that you get from Plot or Show store information on the options they use. You can get this information by applying the Options function to these graphics objects.

 Options[plot] show all the options used for a particular plot Options[plot, option] show the setting for a specific option AbsoluteOptions[plot, option] show the absolute form used for a specific option, even if the setting for the option is Automatic or All

Getting information on options used in plots.
Here is a plot, with default settings for all options.
 In[4]:=  g = Plot[SinIntegral[x], {x, 0, 20}]

 Out[4]=
The setting used for the PlotRange option was All.
 In[5]:=  Options[g, PlotRange]
 Out[5]=
AbsoluteOptions gives the absolute automatically chosen values used for PlotRange.
 In[6]:=  AbsoluteOptions[g, PlotRange]
 Out[6]=

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