Texas Instruments TI86 User Manual - Page 102

90 Chapter 6: Graph Tools In the example, the function y(x)=x^3+.3x2-4x is graphed. Tracing a Graph To display the graph and begin a trace, select TRACE from the GRAPH menu. The trace cursor appears as a small square with a flashing diagonal line at each corner. Initially, the trace cursor appears on the first selected function, at the x value closest to the middle of the screen. If CoordOn format is selected, the cursor coordinates are displayed at the bottom of the screen. When you enter the first character of an independent variable value, an x= prompt is displayed (or q= or t=). The value can be an expression. If the function is undefined at an x value, then the y value is blank. To move the trace cursor... To the next larger or next smaller plotted point in a function To any valid independent-variable value (x, q, or t) on the current equation From one function to another function at x, in the order or reverse order of the selected functions in the equation editor From one member to another member of a family of curves (Chapter 5) Press these keys: " or ! value b # or $ # or $ As you move the trace cursor along a function, the y value is calculated from the x value. That is, y=yn(x). When you trace beyond the top or bottom of the graph screen, the coordinates displayed on the screen continue to change as if the cursor were still on the screen. Panning: To view function coordinates to the left or right of the current graph screen, press and hold ! or " while tracing. When you pan beyond the left or right side of the screen during a trace, the TI-86 automatically changes the values of xMin and xMax.