### Riemann Sums Program code for the CASIO fx-7700GB (or CASIO cfx-9850G Plus) calculator

To enter the program, press MODE then 2 to select WRT mode. Move the cursor to an empty program number, then press EXE. You'll see a blank screen with the blinking cursor at the upper left corner. Now you can proceed to the beginning of the program. When finished, press MODE then 1 to get back to RUN mode.

`
``
"RSUMS"`

"L-LIM"? --> A

"R-LIM"? --> B

"DIVNS"? --> N

A --> X

0 --> S

f_1 --> Y

(B-A) div N --> H

Lbl 1

X + H --> X

f_1 + S --> S

Dsz N

Goto 1

"L-SUM="

(S-f_1+Y)H [display sign]

"R-SUM="

HS

`
`

**Comments on the program listing **
- Take care to distinguish between the character
`1` (one) and
the character `l` (lower case "ell"), and between `0` (zero) and `O` (upper case "oh").
- "
`?`" is accessed by SHIFT, PRGM.
- "
`f_1`" is accessed by SHIFT, F (in a box) MEM, f_n, 1
- "
`Lbl`", "`Dsz`", and "`Goto`" are in JMP menu.
- You can put either a colon ( : ) or a carriage return (EXE) after each instruction (to separate them), except after the display sign, which provides its own carriage return.

**Running the program**

- This program calculates left and right Riemann sums.
- The formula for the integrand (function to be integrated) must be entered into f_1 using X as the indpendet variable.
- The lower limit of integration must be less than the upper limit.
- As a test of the program, evaluate the definite integral of x^3 (x cubed) from A=1 to B=3 using
N=100 subdivisions. The left and right Riemann sums should be 19.7408 and 20.2608, respectively.

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*October 23, 1998*