*General: *
To type an upper case letter, press ALPHA key, followed by the letter.
To begin entering the program, press the PGRM key, and select NEW from
the menu. The calculator will go into ALPHA mode and prompt you to
enter the name. Type in (for example) SLOPE and press ENTER.
The program now displays the colon : which must appear at the
beginning of each command.

To enter the program commands (all the words in the program that
start with a Capital Letter), press PRGM key, then select one of
the two menus:

- CTL (Control commands)
- I/O (Imput-output commands).

When navigating menus, use CLEAR to return to where you were.

This program is more elaborate than the others because it must link the computational and graphing operations of the calculator.

COMMAND: Explanation and keying instructions::FnOff Inactivates function graphing. Y-VARS (2nd VARS),5,2. :ClDrw Clears the screen. DRAW (2nd PRGM),1 :Prompt Xmin,Xmax,Ymin, Ymax Prompts for input of screen parameters. Prompt is PRGM, and 2 from the I/O menu. Xmin, etc. are on the VARS,1 menu. :7(Xmax - Xmin)/83->H Calculates horizontal step-size. - is to the right of 6, / is the division key, which is under the ^ key, -> is STO. :7(Ymax - Ymin)/55->K Calculates vertical step-size. :1/(0.4H)^2->A The numbers A and B are used in calculating :1/(0.4K)^2->B the how long the lines should be. :Xmin+0.5H->X Calculates position of lower left-hand slope line. :Ymin+0.5K->Z Use [X,T,theta] to get X. :1->I Initialize I: counts columns. :Lbl P Labels this program location. Lbl is PRGM, and 9 from the CTL menu. :1->J Initialize J: counts rows. :Z->Y Initialize Y for the current column. :Lbl Q Labels this program location. :Y1->T Program applies expression stored as Y1 to compute the current slope. To get Y1, press Y-VARS and select 1 twice. :1/sqrt(A+B*T^2)->C sqrt is the square-root (2nd x-squared, to the left of comma). * is the times key (next to 9). :T*C->S These two instructions calculate the horizontal and vertical extent of the line segment to be drawn. :X->U Store current X,Y values as U and V. :Y->V :Line(U-C,V-S,U+C,V+S) Draws a line segment through (X,Y). Line( is 2 on the DRAW (2nd PGRM) menu. Comma is the key above 7. :V+K->Y Increment Y. :IS>(J,8) Add 1 to J and test. If less than or equal 8, go to the next instruction (i.e. proceed up the column). If greater, skip next instruction. For IS>(, PGRM, and select A from the CTL menu. :Goto Q For Goto: PGRM, 0 on the CTL menu. :U+H->X Increment X (i.e. move to next column). :IS>(I,12) Test if all columns are done. :Goto P

*Running the program:* First enter the function giving the slope:
Press Y= (below the screen) then type it in on the Y1 line as a function
of the two variables X (use [X,T.theta]) and Y. (e.g. X+Y).
Then QUIT (2nd MODE) to return to home screen.
Now PRGM, select SLOPE from the EXEC menu, ENTER. Enter numbers at the
question mark (?) prompts.

*Check:* For Y1 = -X/Y get circles centered at the origin. The
circles will be round if your screen parameters have the correct aspect ratio.

*Check:* For Y1 = X+Y and window [-3,3]x[-2,2], calculator screen
should have the image shown on the right.

Math Dept SUNY Stony Brook

tony@math.sunysb.edu

September 12 1997