EraseAll       IndepBegin     IndependentVar  Steps         
   Generator      IndepEnd       Plot           Xexpr          
A tool for graphing any set of expressions as a function of an independent variable.

The Grapher is similar to a "for" statement. It iterates the independent variable over the range specified by the "Indep Begin" and "Indep End" field editors using "Steps" steps. At each step, it executes the statements specified in the Generator field (if any), and plots the values that are specified in the Graph scene from the PlotWhat menu item at the x-axis location specified by the value of the "X-expr" (normally the same as the independent variable).

These y values and X-expr can be variable names or function names.

To pop up the widget say:

execute following example

	load_file("grapher.hoc")	// reads this file
	makegrapher(1)			// pop up a new grapher
Creating a grapher using
pops up a short form of the Grapher without "Indep Begin", "Indep End", or "X-expr" buttons. The limits are defined by the x-axis length of the current view.

Graphers may be saved in a .ses file.

To use the grapher widget:

	1) enter the independent variable name (press the button) eg. x
	2) enter the begin, end, and steps values.
	3) specify the y variables:
		in the graph panel press the left button and select "Plot What?"
		and enter an expression or variable to plot. eg. sin(x)
		You can do this several times to plot several expressions.
	4) If the y variables are actual functions of the independent variable
		press the Plot button to see the plot. If the y variables
		are in fact just variables then you will need a generator
		statement that tells how to compute the y variables given
		a value of the independent variable. eg. Just for fun you can
		try entering the generator statement:
			print x, sin(x)


	Example 1: plot sin(t)
	1) PlotWhat: sin(t)
	2) Plot

Example 2: plot of steady state m process in nrniv 1) Independent Var: x 2) Generator: rates_hh(x) 3) IndepBegin -100, Indep End 50 4) Set View: x: -100 50 y: 0 1 5) PlotWhat: minf_hh 6) Plot Example 3: In context of Neuron Main Menu simulation 0) pop up grapher by selecting appropriate "New Graph" submenu item. 1) Independent Var: v_init 2) Generator: init() 3) IndepBegin -100, Indep End 50 4) SetView: x: -100 50 y:cancel 5) PlotWhat: 6) Plot

Example 4: peak inward current during voltage clamp Replace the standard: proc advance() {fadvance()} with a procedure that stores the peak inward current (and possibly sets stoprun=1 when you are past the peak). Then in the Grapher set Steps to 20 the independent variable to the voltage clamp amplitude and the generator to run().


For each value of the independent variable the generator statement is executed (if it exists) and the PlotWhat expressions are plotted.


Removes all expressions from the graph.


Number of independent variable values used to make the graph. For the small grapher, the range of the independent variable is the length of the x-axis.


Dialog appears requesting the variable to be used as the independent variable (default t). If the variable is undefined it will be created.


A statement to be executed after setting a value of the independent variable but before plotting the expressions. This allows plotting of variables that depend implicitly on the independent variable.


For a grapher made with makegrapher(1), specifies initial value of the independent variable.


Specifies final value of independent variable.


A grapher made with makegrapher(1) allows separate specification of independent variable and the x axis plot functions. This allows phase plane plots. The Xexpr may be any function of the independent variable or an implicit function if a generator statement exists.

neuron/stdrun/grapher.hel : May 13 2012