The evaluation of an equation takes no values from the stack — it uses only numbers in the equation and variable values. The value of the equation is returned to the X–register. The LAST X register isn't affected.

Using ENTER for Evaluation

If an equation is displayed in the equation list, you can press ‘to evaluate the equation. (If you're in the process of typing the equation, pressing ‘only ends the equation — it doesn't evaluate it.)

„If the equation is an assignment, only the right–hand side is evaluated. The result is returned to the X–register and stored in the left–hand variable, then the variable is VIEWed in the display. Essentially, ‘finds the value of the left–hand variable.

„If the equation is an equality or expression, the entire equation is evaluated — just as it is for X. The result is returned to the X–register.

Example: Evaluating an Equation with ENTER.

Use the equation from the beginning of this chapter to find the volume of a 35–mm diameter pipe that's 20 meters long.

Keys:Display:Description:

H

#/)ºπº:º

( ™as required)

 

‘

@

 

)

35 g

@

 

 )

20 ‘1000



zg

#/

 

 88)
Displays the desired equation.

Starts evaluating the assignment equation so the value will be stored in V. Prompts for variables on the right–hand side of the equation. The current value for D is 2.5000.

Stores D, prompts for L, whose current value is 16.0000.

Stores L in millimeters; calculates V in cubic millimeters, stores the result in V, and displays V.

Entering and Evaluating Equations 6–11