Here is a link to a text file that has the source code for this program. The ASCII version has some limitations. For example, the "store key" (located near the lower left of the keypad, just above the [ON] key) gets printed as /->/, and variable names, like Y₁, get printed funny as well. While you can "type" the program into your calculator, it is much easier to get a copy from your instructor.

Running The Program

It is best to start by entering your integrand, f(x), in Y₁ before running the program. To run the program, press [PRGM], then select the number corresponding to the RECT program, and then press [ENTER] to start the program. An initial menu screen (with INTEGRATE as the title) should appear. The program is controlled by a series of menu screens, and these are all described briefly below. Most of the time, you will use the SETUP menu to enter valid parameters, return to the MAIN menu, and select the third option (CALC) to see the various approximations to your definite integral.

The Initial INTEGRATE Menu

1. SETUP: Opens the SETUP menu, which allows you to enter a new integrand f(x), new starting value A, stopping value B, number of rectangles N, and other parameters described in the section below for the SETUP menu.
2. DRAW:  Opens the RECT TYPE sub-menu, where you can select the type of rectangles (left, right, or midpoint) to draw.
3. CALC: Calculates values for LEFT(N), RIGHT(N), MID(N), TRAP(N), and SIMP(N), using the current values of parameters. After each value is displayed, you must press [ENTER] to move on to the next approximation. After calculating, the values for LEFT(N), RIGHT(N), MID(N), TRAP(N), and SIMP(N) are saved in the variables with names L, R, M, T, and S respectively.
4. SHOW: This displays the current values for A, B, N, and the graphing window variables.
5. QUIT: This ends the program.

The SETUP Menu

1. NEW Y1: Allows you to enter a new formula for the integrand. You MUST enter the formula inside quotes, so for example to integrate x^2, you would type "X^2" after selecting this menu item.
2. NEW A, B: Allows you to enter new starting and stopping values for your definite integral approximation.
3. NEW N: Allows you to enter a new value for the number of "rectangles".
4. WINDOW: Allows you to enter new values for the graphing window, in case you want to use the DRAW feature.
5. MAIN: Returns you to the original INTEGRATE menu.
6. SHOW:  This displays the current values for A, B, N, and the graphing window variables.
7. QUIT:  This ends the program.

The DRAW or RECT TYPE Menu

1. LEFT: Draws left hand sum rectangles.
2. RIGHT: Draws right hand sum rectangles.
3. MID: Draws midpoint rectangles.
   
4. SETUP: Takes you to the SETUP menu.
   
5. MAIN: Returns you to the original INTEGRATE menu.
6. QUIT:  This ends the program.