Graphmatica allows you to specify the domain of each equation independently. This allows you to draw only a particular part of a graph or change the domain without using the Range or Theta range functions to change the default domain. To specify a domain for an equation, type anywhere on the line the expression

{ m, n }

where m is the start of the domain and n is the end. If you want the domain to start at the default start, leave m out. Then, whatever you change the start of the default domain to, that will always be where the equations starts graphing. To leave the end of the domain open, leave out n. So if the range on-screen is (-10,10), specifying a domain of { ,5} will graph from -10 to 5, and one of {-4, } will go from -4 to 10.

If you prefer, for Cartesian equations, you can also use the Unicode infinity symbol (∞) to specify an open domain explicitly instead of leaving one end of the domain blank. For example:

 { -∞, 2 }

To graph a parametric equation, you must specify a domain that is closed (i.e. one that has neither number left out). When entering a parametric equation, you also have the option of specifying the step rate for the equation by adding a third clause to the domain. ({start, stop, step by})

The domain is parsed like any other expression, so you can use all of the arithmetic operators and functions available in the rest of the equations, as well as numbers and the constants d, e, and pi. The only restriction is that you may not use a variable (including free variables--see the Operator Table for a list) in your domain, since this would yield ambiguous results.

When specifying domains for polar functions, you may find it easier to give the domain in radians as a multiple of pi (such as {-2pi, 2pi}) or in degrees (like {0, 180d}, where d is the built-in constant that converts degrees to radians).


To be more precise about whether the endpoints of the domain are included or excluded from the function definition, you can use interval notation instead. Use a square bracket to indicate that the domain includes the specified value, or a paren to indicate that the value is excluded. Examples:

{ [0, 7) } x >=0 and x < 7
{ ( , 7) } x < 7
{ [7, ) } x >= 7

When you specify a domain using interval notation, Graphmatica will add endcaps to the plot: an open circle to indicate an excluded endpoint or a closed dot to indicate an included endpoint.

You may define single-point domains like {[0,0]}. However, empty domains like {[0,0)} or {(1,1)} are not allowed.

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kSoft, Inc. ksoft@graphmatica.com Last updated: Sun 11 Jun 2017