HP 33s hp 33s_user's manual_English_E_HDPM20PIE56.pdf - Page 218

2. Select the program that defines the function to integrate: press | W label. (You can skip this step if you're reintegrating the same program.) 3. Enter the limits of integration: key in the lower limit and press ‘, then key in the upper limit. 4. Select the variable of integration and start the calculation: press |  variable. Notice that FN= is required if you're integrating a programmed function, but not if you're integrating an equation from the equation list. You can halt a running integration calculation by pressing ‡ or g. However, the calculation cannot be resumed. To write a program for ³ FN: The program can use equations, ALG or RPN operations - in whatever combination is most convenient. 1. Begin the program with a label. This label identifies the function that you want to integrate (/label). 2. Include an INPUT instruction for each variable, including the variable of integration. INPUT instructions enable you to integrate with respect to any variable in a multi-variable function. INPUT for the variable of integration is ignored by the calculator, so you need to write only one program that contains a separate INPUT instruction for every variable (including the variable of integration). If you include no INPUT instructions, the program uses the values stored in the variables or entered at equation prompts. 3. Enter the instructions to evaluate the function. „ A function programmed as a multi-line RPN or ALG sequence must calculate the function values you want to integrate. „ A function programmed as an equation is usually included as an expression specifying the integrand - though it can be any type of equation. If you want the equation to prompt for variable values instead of including INPUT instructions, make sure flag 11 is set. 4. End the program with a RTN. Program execution should end with the value of the function in the X-register. 14-8 Solving and Integrating Programs