Java Scientific Calculator


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Creating graphs of functions

The calculator can create graphs of various expressions. To create a graph, evaluate an expression and use the Graph button (keys shift, ‘G’) to display a graph.

At May 2008 the calculator only displays graphs of the form y = f(x) where f(x) is the most recently evaluated expression. The graph is restricted to real-valued functions or parts of functions. So, for example, the graph of sqrt( x ) shows no values for x &less; 0. The range of x displayed must also be real.

If the expression is a real constant the graph displays nothing more than a horizontal line with y equal to the constant value. To get more interesting graphs, enter a variable expression using the x button and then create a graph from the evaluated expression: that is, use the equals button to evaluate the expression and then use the Graph button to display the graph.

Although you can change the size of the graph display, showing more or less of the graph, the default scale is not necessarily what you want. For example, to display sin( x ) you might want x to range from −180 (degrees) to 180 and y to range from −1 to 1. These ranges would not be suitable for displaying x2.

You can use the menu on the graph to change various properties of the axes of the graph. These include the minimum and maximum value shown on the axis and the units to be shown on the axis. The major unit has longer ticks and shows numbers next to each tick. For cos( x ) you might choose major units of 30 (degrees) on the x axis, but a major unit of 0.2 on the y axis. The minor unit has ticks but no numbers and must be an postive integral divisor of the major unit. You can choose whether or not to display either major or minor units.

At May 2008 the graph features should not be considered fully stable. They have not been tested extensively, as the numerical calculations have and there are some known issues in displaying graphs.

Last modified: Sat 31 May 2008 01:10 pm Logo