Interactive Manual › Chapter 8

Chapter 8: Draw Instructions

Draw on top of a graph: lines, tangents, functions, inverses, shaded regions, circles, text, free-hand pen strokes, points and pixels, and save graphs as pictures (Pic) or graph databases (GDB). Covers the DRAW, DRAW POINTS and DRAW STO menus.

Getting Started: Drawing a Tangent Linep. 121

In this activity you find the equation of the tangent line to Y=sin(X) at X=√2/2. The calculator draws the line for you and prints the point and the line equation at the bottom of the graph.

Tutorial

Draw the tangent line to sin(X) at X=√2/2

The calculator should be in Radian and Func mode (the defaults). Reset first if you changed them.

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Open the Y= editor and enter sin(X) in Y₁.
Y=SINX,T,θ,n)
Graph it in the Zoom Trig window: ZOOM7 selects 7:ZTrig.
ZOOM7
Open the DRAW menu with 2ndDRAW and choose 5:Tangent(. The calculator is now waiting for you to say where to draw the tangent.
2ndDRAW5
Type the X value, √2÷2, and press ENTER. The cursor jumps to that X value on the curve; when you press ENTER the tangent line is drawn, and the X value and the equation of the line appear at the bottom of the screen.
2nd√2)÷2ENTER
Try repeating the activity with the decimal setting on the MODE screen changed from Float to a fixed number of places. The X value and the equation then show fewer digits.

Using the DRAW Menup. 122

Press 2ndDRAW to open the DRAW menu. It has three tabs: DRAW (lines, curves, shading, circles, text and the pen), POINTS (points and pixels) and STO (saving pictures and graph databases). Use ▶︎ and ◀︎ to move between tabs.

The same menu behaves in two ways. If a graph is on the screen when you pick an item, most instructions become interactive: you place the cursor and press ENTER to draw. If you open the menu from the home screen or from the program editor, the instruction is simply pasted at the cursor so you can finish typing it and run it as a command.

Before Drawing on a Graphp. 122

Drawings are laid on top of a graph, so get the graph the way you want it first. Before you draw, think about whether you need to do any of the following:

Change the mode settings on the MODE screen.
Change the format settings on the FORMAT screen. You can press 2ndFORMAT or use the shortcut on the MODE screen.
Enter or edit functions in the Y= editor.
Select or deselect functions in the Y= editor.
Change the window variable values.
Turn stat plots on or off.
Clear existing drawings with ClrDraw.

Note If you draw on a graph and then do any of the things listed above, the graph is replotted without your drawings the next time it is displayed. Drawings are temporary. To keep them, save the picture with StorePic before you make the change (see Storing a Graph Picture).

Drawing on a Graphp. 123

Every DRAW instruction except DrawInv works on Func, Par, Pol and Seq graphs. DrawInv only works in Func graphing. All coordinates you give to DRAW instructions are the graph's own x- and y-values (as set by the window), except the pixel instructions and Text(, which use pixel positions.

Most instructions in the DRAW and DRAW POINTS menus can be used directly on a displayed graph, with the cursor choosing the coordinates. You can also run them from the home screen or from inside a program. Selecting an instruction from the menu when no graph is displayed returns you to the home screen.

Clearing Drawingsp. 123

ClrDraw

ClrDraw

Erases every point, line, circle, shaded area and piece of text that DRAW instructions have put on the current graph. The graph itself is plotted again with nothing drawn on it.

Where: 2ndDRAW 1:ClrDraw

Keys: 2ndDRAW1

ClrDraw ENTER on the home screen prints Done.

All points, lines and shading drawn on a graph are temporary. They disappear when you run ClrDraw and also when the graph is replotted after a change (see Before Drawing on a Graph). Save the picture with StorePic first if you want to be able to get it back.

Tutorial

Clear drawings while a graph is displayed

Choosing ClrDraw with a graph on screen replots the graph straight away.

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Show the graph. The horizontal line at Y=2 drawn earlier is still on it (pixel row 25).
GRAPH
Open the DRAW menu and pick 1:ClrDraw. The graph is replotted with no drawn elements.
2ndDRAW1

Tutorial

Clear drawings from the home screen

From the home screen or a program, ClrDraw is a command that you run.

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

On a blank home-screen line, open the DRAW menu and select 1:ClrDraw. It is pasted at the cursor.
2ndDRAW1
Press ENTER to run it. The calculator shows Done, and the next time you display the graph all drawn elements are gone.
ENTER

Drawing Line Segmentsp. 124

Line(

Line(X1,Y1,X2,Y2)Line(X1,Y1,X2,Y2,0)

Draws the segment from (X1,Y1) to (X2,Y2). The values can be expressions. Add a final argument of 0 to erase a segment (turn its pixels off) instead of drawing it.

Where: 2ndDRAW 2:Line(

Keys: 2ndDRAW2

Line(⁻5,⁻3,5,⁻3) draws a horizontal segment 10 units long
Line(⁻5,⁻3,5,⁻3,0) erases it again

To draw a segment directly on a displayed graph, pick 2:Line(, put the cursor on the start point and press ENTER, then move the cursor to the end point (a line follows the cursor as you move) and press ENTER again. Keep going to chain more segments: each new segment starts where the last one ended. Press CLEAR to cancel Line(.

Tutorial

Draw a line segment with the cursor

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Display the graph.
GRAPH
Open the DRAW menu and select 2:Line(.
2ndDRAW2
Move the cursor a little to the left of the origin with ◀︎. This will be the start point. Press ENTER to anchor it.
◀︎◀︎◀︎◀︎◀︎ENTER
Move the cursor to the right. A line is drawn from the start point to the cursor as you move. Press ENTER to fix the end point.
▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎ENTER
Press CLEAR to cancel Line(. The segment stays on the graph.
CLEAR

Tutorial

Draw and erase a line segment from the home screen

Run Line( as a command to draw between exact coordinates in the standard window.

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

On the home screen, open the DRAW menu and select 2:Line(.
2ndDRAW2
Type the four coordinates X1,Y1,X2,Y2: from (⁻5,⁻3) to (5,⁻3). Press ENTER to draw.
(−)5,(−)3,5,(−)3)ENTER
Go back to the home screen with 2ndQUIT. To erase that segment, run the same instruction with a fifth argument of 0. Recall the last entry with 2ndENTRY, then edit it: press ◀︎ to get to the closing parenthesis and type ,0.
2ndQUIT2ndENTRY◀︎,0ENTER

Drawing Horizontal and Vertical Linesp. 125

On a displayed graph, pick 3:Horizontal or 4:Vertical. A line appears and follows the cursor as you move it. Put the cursor at the y-value (horizontal) or x-value (vertical) you want, and press ENTER to draw the line. Repeat to draw more lines, and press CLEAR to cancel.

Horizontal

Horizontal y

Draws a horizontal line across the whole graph at Y=y. The value y can be an expression but not a list.

Where: 2ndDRAW 3:Horizontal

Keys: 2ndDRAW3

Horizontal 2 draws the line Y=2

Vertical

Vertical x

Draws a vertical line across the whole graph at X=x. The value x can be an expression but not a list.

Where: 2ndDRAW 4:Vertical

Keys: 2ndDRAW4

Vertical ⁻3 draws the line X=⁻3

Tip To draw more than one horizontal or vertical line from the home screen or a program, separate the instructions with a colon (ALPHA:), for example Horizontal 2:Vertical ⁻3.

Tutorial

Draw a horizontal line with the cursor

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Display the graph.
GRAPH
Select 3:Horizontal from the DRAW menu.
2ndDRAW3
Move the cursor up. A horizontal line moves with it. Stop when it is above the x-axis.
▲︎▲︎▲︎▲︎▲︎▲︎
Press ENTER to draw the line. Then press CLEAR to cancel.
ENTERCLEAR

Tutorial

Draw a vertical line with the cursor

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Display the graph.
GRAPH
Select 4:Vertical from the DRAW menu.
2ndDRAW4
Move the cursor to the left of the y-axis.
◀︎◀︎◀︎◀︎◀︎◀︎◀︎◀︎◀︎◀︎
Press ENTER to draw the line, then CLEAR to cancel.
ENTERCLEAR

Tutorial

Draw horizontal and vertical lines from the home screen

Two instructions on one line, joined with a colon.

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 3:Horizontal from the DRAW menu and type the y-value, 2.
2ndDRAW32
Type a colon (ALPHA:), select 4:Vertical, and type ⁻3.
ALPHA:2ndDRAW4(−)3
Press ENTER. Both lines are drawn.
ENTER

Drawing Tangent Linesp. 126

To draw a tangent on a displayed graph, pick 5:Tangent( and follow these steps.

Press ▼︎ and ▲︎ to move the cursor to the function you want a tangent to. If ExprOn is selected in the format settings, the Y= expression of the current graph is shown in the top-left corner.
Press ▶︎ and ◀︎, or type a number, to choose the point on the function.
Press ENTER. In Func mode the X value and the tangent-line equation appear at the bottom of the screen. In the other graphing modes the dy/dx value is shown instead.
To see fewer digits in X and in the equation, change the fixed-decimal setting on the MODE screen.

Tangent(

Tangent(expression,value)

Draws the line tangent to expression (an expression in X, such as Y₁ or X²) at the point X=value. The value can be an expression. The expression is always interpreted as a Func-mode expression.

Where: 2ndDRAW 5:Tangent(

Keys: 2ndDRAW5

Tangent(X²,1) draws the line Y=2X−1 touching the parabola at X=1

Tutorial

Choose a function and point with the cursor

This time you steer with the arrow keys instead of typing the X value.

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

The parabola Y₁=X² is graphed in the standard window. Select 5:Tangent( from the DRAW menu.
2ndDRAW5
The cursor is on Y₁ at X=0. Press ▶︎ a few times to slide it along the curve.
▶︎▶︎▶︎▶︎▶︎
Press ENTER to draw the tangent line at the cursor.
ENTER

Tutorial

Draw a tangent from the home screen

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 5:Tangent( from the DRAW menu. Enter the expression X², a comma and the X value 1.
2ndDRAW5X,T,θ,nx²,1)
Press ENTER. The graph appears with the tangent Y=2X−1 drawn through the point (1,1).
ENTER

Drawing Functions and Inversesp. 127

Drawing a Functionp. 127

DrawF

DrawF expression

Draws expression (an expression in X) on the current graph as if it were a function, without putting it in the Y= editor. It is not interactive: choosing 6:DrawF from the menu returns you to the home screen or program editor so you can type the expression.

Where: 2ndDRAW 6:DrawF

Keys: 2ndDRAW6

DrawF X²−2

Note You cannot use a list in the expression to draw a family of curves with DrawF.

Tutorial

Draw a function without entering it in Y=

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 6:DrawF from the DRAW menu, then type the expression X²−2.
2ndDRAW6X,T,θ,nx²−2
Press ENTER. The parabola is drawn on the graph. It passes through (0,⁻2), which is near pixel row 37.
ENTER

Drawing an Inverse of a Functionp. 127

DrawInv

DrawInv expression

Draws the inverse of expression by plotting its X values on the y-axis and its Y values on the x-axis (the curve reflected in the line Y=X). It is not interactive: choosing 8:DrawInv returns you to the home screen or program editor. It works in Func mode only.

Where: 2ndDRAW 8:DrawInv

Keys: 2ndDRAW8

DrawInv X² draws the sideways parabola X=Y²

Note You cannot use a list of expressions with DrawInv.

Tutorial

Draw the inverse of X²

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 8:DrawInv and type X².
2ndDRAW8X,T,θ,nx²
Press ENTER. The sideways parabola X=Y² opens to the right: at Y=3 it reaches X=9, near the right-hand edge of the screen.
ENTER

Shading Areas on a Graphp. 128

Shade( is not interactive: choosing 7:Shade( pastes it into the home screen or the program editor so you can type the arguments.

Shade(

Shade(lowerfunc,upperfunc[,Xleft,Xright,pattern,patres])

Draws lowerfunc and upperfunc (both in terms of X) on the current graph and shades the area that is above lowerfunc and below upperfunc. Only the places where lowerfunc < upperfunc are shaded. Xleft and Xright optionally limit the shading to a left and right boundary; they must be between Xmin and Xmax, which are the defaults. pattern picks one of four shading patterns and patres one of eight shading resolutions.

Where: 2ndDRAW 7:Shade(

Keys: 2ndDRAW7

Shade(X²−4,4) shades between the parabola and the line Y=4
Shade(⁻5,X²,⁻3,3,3,2) shades from Y=⁻5 up to X² between X=⁻3 and X=3 using diagonal lines on every second pixel

Shading patterns
pattern	Shading
1	vertical lines (default)
2	horizontal lines
3	negative-slope 45° lines
4	positive-slope 45° lines

Shading resolutions
patres	Pixels shaded
1	every pixel (default)
2	every second pixel
3	every third pixel
4	every fourth pixel
5	every fifth pixel
6	every sixth pixel
7	every seventh pixel
8	every eighth pixel

Tutorial

Shade the area between two functions

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 7:Shade( from the DRAW menu. Enter the lower function X²−4, a comma, and the upper function 4.
2ndDRAW7X,T,θ,nx²−4,4)
Press ENTER. The region above the parabola and below the line Y=4 is shaded.
ENTER

Tutorial

Limit the shading with Xleft, Xright, pattern and patres

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 7:Shade( and enter lower function ⁻5, upper function X², then Xleft ⁻3 and Xright 3.
2ndDRAW7(−)5,X,T,θ,nx²,(−)3,3
Add the pattern (2 = horizontal lines) and the resolution (2 = every second pixel). Close the parenthesis and press ENTER.
,2,2)ENTER
The area is shaded only between X=⁻3 and X=3. Pixels outside those boundaries, such as the column near X=⁻6, stay clear.

Drawing Circlesp. 128

Circle(

Circle(X,Y,radius)

Draws a circle with centre (X,Y) and the given radius, in graph units. All three values can be expressions.

Where: 2ndDRAW 9:Circle(

Keys: 2ndDRAW9

Circle(0,0,5)

To draw a circle directly on a displayed graph, pick 9:Circle(, put the cursor at the centre and press ENTER, then move the cursor to any point on the circumference and press ENTER again. Repeat to draw more circles, or press CLEAR to cancel.

Note A circle drawn with the cursor is round on the screen whatever the window settings are, because it is drawn directly on the display. A circle drawn with the Circle( command from the home screen or a program is measured in graph units, so an uneven window can stretch it into an ellipse. Run ZSquare (Chapter 3) first to make the circle look round.

Tutorial

Draw a circle with the cursor

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Display the graph.
GRAPH
Select 9:Circle(. Move the cursor to the centre of the circle (the origin is fine) and press ENTER.
2ndDRAW9ENTER
Move the cursor to the right to a point on the circumference. The distance from the centre is the radius. Press ENTER to draw the circle.
▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎ENTER
Press CLEAR to cancel Circle(.
CLEAR

Tutorial

Draw a circle from the home screen

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 9:Circle( from the DRAW menu and enter the centre (0,0) and radius 5.
2ndDRAW90,0,5)
Press ENTER. In the standard window one pixel is a different distance across than it is down, so the circle comes out as a wide oval. Run ZSquare first for a perfectly round one.
ENTER

Placing Text on a Graphp. 129

Text(

Text(row,column,value,value…)

Writes the characters of each value on the current graph, starting with the top-left corner of the first character at pixel (row,column). row is an integer from 0 to 57 and column an integer from 0 to 94; both can be expressions. A value can be text in quotation marks or an expression, which is evaluated and shown with up to 10 characters. Values can include functions and instructions.

Where: 2ndDRAW 0:Text(

Keys: 2ndDRAW0

Text(0,0,"HI")
Text(20,30,"A=",A)

To place text directly on a displayed graph, pick 0:Text(, move the cursor to where the text should start, then type the characters. Use ALPHA or 2ndA-LOCK to type letters and θ; you can also enter functions, variables and instructions. The font is proportional, so how many characters fit across the screen depends on which ones you type. Press CLEAR to cancel.

Note On a Horiz split screen the largest row is 25. On a G-T split screen the largest row is 45 and the largest column is 46. Split screens are covered in Chapter 9.

Tutorial

Write text on a graph with the cursor

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Display the graph.
GRAPH
Select 0:Text(. Move the cursor to where the text should start; here, some way up and to the left of the origin.
2ndDRAW0◀︎◀︎◀︎◀︎◀︎◀︎◀︎◀︎◀︎◀︎▲︎▲︎▲︎▲︎▲︎▲︎▲︎▲︎▲︎▲︎
Type the letters H and I (each is ALPHA plus the key that carries it).
ALPHAHALPHAI
Press CLEAR to cancel Text(.
CLEAR

Tutorial

Write text on a graph from the home screen

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 0:Text( from the DRAW menu. Type the row 0 and the column 0, then a comma and an opening quotation mark (ALPHA").
2ndDRAW00,0,ALPHA"
Type the letters H and I, then close the quote with ALPHA" and the parenthesis.
ALPHAHALPHAIALPHA")
Press ENTER. The text is written in the top-left corner of the graph.
ENTER

Using Pen to Draw on a Graphp. 130

Pen

Pen

A free-hand drawing tool. It works only directly on a displayed graph; you cannot run it from the home screen or from a program. Press ENTER to put the pen down, move the cursor to draw (one pixel at a time), and press ENTER to lift it again.

Where: 2ndDRAW A:Pen

Keys: 2ndDRAW▲︎

Select A:Pen from the DRAW menu.
Place the cursor at the point where you want to begin and press ENTER to turn the pen on.
Move the cursor. Each pixel it passes over is turned on, so you draw on the graph.
Press ENTER to turn the pen off. To start a new stroke, move to a new place and repeat from step 2.
Press CLEAR to cancel Pen.

Tip Pen is handy for annotating a graph, for example drawing an arrow that points at a minimum. Store the result with StorePic (see Storing a Graph Picture) to keep it. On a real calculator the picture could also be copied to a computer with TI-Connect; that does not apply to this emulator.

Tutorial

Draw a stroke with Pen

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Display the graph.
GRAPH
Open the DRAW menu. A:Pen is the last item, so press ▲︎ to jump to the bottom of the list and then ENTER to choose it.
2ndDRAW▲︎ENTER
Press ENTER to put the pen down at the cursor (the middle of the screen), then move ▶︎ five times to draw a stroke.
ENTER▶︎▶︎▶︎▶︎▶︎
Press ENTER to lift the pen, move ▼︎ twice (nothing is drawn now), then press CLEAR to cancel.
ENTER▼︎▼︎CLEAR

Drawing Points on a Graphp. 131

Press 2ndDRAW then ▶︎ to display the DRAW POINTS menu. As with the DRAW menu, an instruction picked while a graph is displayed is interactive for the three Pt- instructions, whereas the pixel instructions always return to the home screen or program editor.

Drawing Points Directly on a Graph with Pt-On(p. 131

To draw a point on a displayed graph: pick 1:Pt-On(, move the cursor to the spot, and press ENTER. Repeat to add more points, and press CLEAR to cancel.

Tutorial

Draw points with the cursor

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Display the graph.
GRAPH
Open the DRAW menu, move to the POINTS tab with ▶︎, and select 1:Pt-On(.
2ndDRAW▶︎1
Move the cursor to the right of the origin and press ENTER to place a point. Move again and press ENTER for another point.
▶︎▶︎▶︎ENTER▶︎▶︎▶︎ENTER
Press CLEAR to cancel Pt-On(.
CLEAR

Erasing Points with Pt-Off(p. 132

To erase a drawn point: pick 2:Pt-Off(, move the cursor to the point and press ENTER. Repeat for other points and press CLEAR to cancel.

Tutorial

Erase a point with the cursor

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

The standard-window graph already has a point drawn at (2,3), which is pixel row 22, column 56. Display the graph.
GRAPH
Select 2:Pt-Off( from the POINTS tab.
2ndDRAW▶︎2
Move the cursor onto the point: 9 steps right and 9 steps up from the centre. Press ENTER to erase it.
▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎▶︎▲︎▲︎▲︎▲︎▲︎▲︎▲︎▲︎▲︎ENTER
Press CLEAR to cancel.
CLEAR

Changing Points with Pt-Change(p. 132

To toggle a point: pick 3:Pt-Change(, move the cursor to the point and press ENTER. If the point was on, it turns off; if it was off, it turns on. Repeat for others and press CLEAR to cancel.

Tutorial

Toggle a point with the cursor

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Display the graph.
GRAPH
Select 3:Pt-Change( from the POINTS tab, move the cursor off the axes (up and to the right of the origin), and press ENTER. The point turns on.
2ndDRAW▶︎3▶︎▶︎▲︎▲︎ENTER
Press ENTER again at the same spot. The point toggles off.
ENTER
Press CLEAR to cancel.
CLEAR

Drawing Points from the Home Screen or a Programp. 132

Pt-On( turns on the point at (X=x, Y=y), Pt-Off( turns it off and Pt-Change( toggles it. The optional mark decides how the point looks:

mark	Appearance
1	dot (default)
2	box
3	cross (+)

Pt-On(

Pt-On(x,y[,mark])

Turns on the point at graph coordinates (x,y). mark is 1 (dot, the default), 2 (box) or 3 (cross).

Where: 2ndDRAW ▶︎ 1:Pt-On(

Keys: 2ndDRAW▶︎1

Pt-On(2,3)
Pt-On(2,3,3) draws a cross

Pt-Off(

Pt-Off(x,y[,mark])

Turns off the point at graph coordinates (x,y). mark works as for Pt-On(.

Where: 2ndDRAW ▶︎ 2:Pt-Off(

Keys: 2ndDRAW▶︎2

Pt-Off(2,3)

Pt-Change(

Pt-Change(x,y)

Toggles the point at graph coordinates (x,y): on becomes off and off becomes on. It has no mark argument.

Where: 2ndDRAW ▶︎ 3:Pt-Change(

Keys: 2ndDRAW▶︎3

Pt-Change(2,3)

Note If you turned a point on with a mark value, you must give the same mark to Pt-Off( to turn it off. Pt-Change( does not take a mark.

Tutorial

Draw and erase points from the home screen

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 1:Pt-On( from the POINTS tab and type the point (2,3) with mark 3 (a cross).
2ndDRAW▶︎12,3,3)
Press ENTER. A small cross appears at (2,3), centred on pixel row 22, column 56.
ENTER
Return to the home screen and select 2:Pt-Off( from the POINTS tab. Type the same point and the same mark of 3, which is needed to erase the cross.
2ndQUIT2ndDRAW▶︎22,3,3)
Press ENTER to erase the cross.
ENTER

Drawing Pixelsp. 132

A pixel is one square dot of the 96×64 display. The Pxl- instructions turn a pixel on, turn it off, or reverse it, addressing it by row and column rather than by graph coordinates. They are not interactive: choosing one from the DRAW POINTS menu always returns you to the home screen or the program editor.

On the graph screen, row is an integer from 0 to 62 (top to bottom) and column an integer from 0 to 94 (left to right).

Turning On and Off Pixels with Pxl-On( and Pxl-Off(p. 133

Pxl-On(

Pxl-On(row,column)

Turns on the pixel at (row,column). row is an integer from 0 to 62 and column an integer from 0 to 94.

Where: 2ndDRAW ▶︎ 4:Pxl-On(

Keys: 2ndDRAW▶︎4

Pxl-On(10,20)

Pxl-Off(

Pxl-Off(row,column)

Turns off the pixel at (row,column).

Where: 2ndDRAW ▶︎ 5:Pxl-Off(

Keys: 2ndDRAW▶︎5

Pxl-Off(10,20)

Pxl-Change(

Pxl-Change(row,column)

Toggles the pixel at (row,column): on becomes off and off becomes on.

Where: 2ndDRAW ▶︎ 6:Pxl-Change(

Keys: 2ndDRAW▶︎6

Pxl-Change(10,20)

Tutorial

Turn pixels on, off and over

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 4:Pxl-On( from the POINTS tab and turn on the pixel in row 10, column 20.
2ndDRAW▶︎410,20)ENTER
Go back to the home screen. Reverse the same pixel with 6:Pxl-Change(; it turns off.
2ndQUIT2ndDRAW▶︎610,20)ENTER
Turn it on again with Pxl-Change(, then turn it off with 5:Pxl-Off(.
2ndQUIT2ndDRAW▶︎610,20)ENTER2ndQUIT2ndDRAW▶︎510,20)ENTER

Using pxl-Test(p. 133

pxl-Test(

pxl-Test(row,column)

Returns 1 if the pixel at (row,column) on the current graph is turned on, or 0 if it is turned off. row must be an integer from 0 to 62 and column an integer from 0 to 94.

Where: 2ndDRAW ▶︎ 7:pxl-Test(

Keys: 2ndDRAW▶︎7

pxl-Test(31,47) is 1 on a standard graph, because the axes cross there

Tutorial

Test whether a pixel is on

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 7:pxl-Test( from the POINTS tab and ask about the pixel you turned on, row 10, column 20.
2ndDRAW▶︎710,20)ENTER
Test a pixel that is off, row 10, column 21. The answer is 0.
2ndDRAW▶︎710,21)ENTER

Note On a Horiz split screen the largest row is 30 for Pxl-On(, Pxl-Off(, Pxl-Change( and pxl-Test(. On a G-T split screen the largest row is 50 and the largest column is 46 for all four. Going beyond the limit causes a DOMAIN error.

Storing Graph Pictures (Pic)p. 134

Press 2ndDRAW then ◀︎ to display the DRAW STO menu. The picture and graph-database instructions are not interactive: picking one returns you to the home screen or program editor.

Storing a Graph Picturep. 134

You can keep up to 10 pictures, each a snapshot of the current graph display, in the picture variables Pic1 to Pic9 and Pic0. Later you can lay a stored picture on top of a displayed graph from the home screen or a program.

A picture contains the drawn elements, the plotted functions, the axes and the tick marks. It does not contain axis labels, the lower and upper bound indicators, prompts or cursor coordinates. Any part of the display those items were hiding is stored too.

StorePic

StorePic nStorePic Picn

Displays the current graph and stores it as picture n (a whole number from 1 to 9, or 0). You can also paste a picture variable from the PICTURE secondary menu, VARS 4:Picture….

Where: 2ndDRAW ◀︎ 1:StorePic

Keys: 2ndDRAW◀︎1

StorePic 3 stores the graph in Pic3

Tutorial

Store a graph picture

You will draw a horizontal line on the graph and save the picture as Pic1.

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 1:StorePic from the DRAW STO tab. It is pasted at the cursor.
2ndDRAW◀︎1
Enter the number of the picture variable, 1.
1
Press ENTER. The current graph, including the line, is stored in Pic1.
ENTER
To prove that the picture holds the line, erase the drawings with ClrDraw (2ndDRAW 1, then ENTER).
2ndDRAW1ENTER
Now recall the picture: RecallPic 1 (2ndDRAW ◀︎ 2, then 1 and ENTER). The line is back.
2ndDRAW◀︎21ENTER

Recalling a Graph Picturep. 135

RecallPic

RecallPic nRecallPic Picn

Displays the current graph with stored picture n (a whole number from 1 to 9, or 0) laid on top of it. You can also paste a picture variable from the PICTURE secondary menu, VARS 4:Picture….

Where: 2ndDRAW ◀︎ 2:RecallPic

Keys: 2ndDRAW◀︎2

RecallPic 3

Note Pictures are just drawings. You cannot trace a curve that is part of a picture.

To delete pictures from memory, use the MEMORY MANAGEMENT / DELETE secondary menu (Chapter 18).

Tutorial

Recall a stored picture

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Pic1 holds a graph with a line at Y=2, but the current graph has had its drawings cleared. Select 2:RecallPic from the DRAW STO tab.
2ndDRAW◀︎2
Enter the picture number, 1. You could also paste Pic1 from the PICTURE menu, VARS 4.
1
Press ENTER. The graph is displayed with the saved line back on top of it.
ENTER

Storing Graph Databases (GDB)p. 135

A graph database (GDB) holds the set of elements that define a graph, so you can recreate that graph later. You can keep up to 10 of them, in GDB1 to GDB9 and GDB0.

A GDB stores five things:

The graphing mode (Func, Par, Pol or Seq).
The window variables.
The format settings.
All the functions in the Y= editor and whether each is selected.
The graph style of each Y= function.

Note A GDB does not contain drawn items or stat plot definitions.

Storing a Graph Databasep. 135

StoreGDB

StoreGDB nStoreGDB GDBn

Stores the current graph database in GDB variable n (a whole number from 1 to 9, or 0). You can also paste a variable from the GDB secondary menu, VARS 3:GDB….

Where: 2ndDRAW ◀︎ 3:StoreGDB

Keys: 2ndDRAW◀︎3

StoreGDB 7 stores the current graph setup in GDB7

Tutorial

Store the current graph in a GDB

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

The calculator has Y₁=X² and a window of ⁻5 to 5. Select 3:StoreGDB from the DRAW STO tab.
2ndDRAW◀︎3
Enter the GDB number, 7. (You could instead paste GDB7 from the GDB menu, VARS 3.)
7
Press ENTER. Y₁, the window and the other graph settings are stored in GDB7.
ENTER

Recalling a Graph Databasep. 136

Note Caution: recalling a GDB replaces all existing Y= functions. If you want to keep what is in the Y= editor, store it in another GDB first.

RecallGDB

RecallGDB nRecallGDB GDBn

Replaces the current graph database with the one stored in GDB variable n (a whole number from 1 to 9, or 0). The new graph is not plotted automatically; press GRAPH to see it. The graphing mode is changed automatically if the stored graph used a different one. You can also paste a variable from the GDB secondary menu, VARS 3:GDB….

Where: 2ndDRAW ◀︎ 4:RecallGDB

Keys: 2ndDRAW◀︎4

RecallGDB 7

To delete a GDB from memory, use the MEMORY MANAGEMENT / DELETE secondary menu (Chapter 18).

Tutorial

Recall a stored graph database

GDB7 holds Y₁=X² with a window of ⁻5 to 5. The current Y₁ and window have since been changed.

▶ Try this step-by-step on the online TI-84 Plus — keys light up as you go

Select 4:RecallGDB from the DRAW STO tab and enter 7.
2ndDRAW◀︎47
Press ENTER. Y₁ and the window are restored from GDB7 (Y₁=X², window ⁻5 to 5). The graph itself is not drawn yet.
ENTER
Press GRAPH to plot the recalled graph.
GRAPH

1:StorePic	Stores the current picture.
2:RecallPic	Recalls a saved picture.
3:StoreGDB	Stores the current graph database.
4:RecallGDB	Recalls a saved graph database.