EXPRESSION EVALUATOR...
This routine lets you write a mathematical expression,
enter numeric values for the expression variables, and have the computer
solve it for X and (optionally) Y values. The program parses the expression into components and performs
the operations.
The expression evaluator understands the following
symbols (upper or lower case entries are OK):
- Simple operators: + - * / ^ ( )
- Complex operators: EXP, LOG or
LN, LOG10, SIN, COS, TAN, ATN or ATAN, ABS, INT, SQR (square), SQRT (square
root)
- Two special variables (i.e., channels) named "X" and
"Y", chosen with push-buttons (see image below)
- PI (or the equivalent Greek letter)
- Numbers (such as 5, -3.1889, and
1e-10)
- You can add a comment at the end of your expression, delineated
with the " ` " character.
Some general considerations:
- You can store and retrieve up to 4 expressions using the 'Retrieve Expression x' and 'Store as Expression x' popup menus. This will save the trouble (and error potential) of re-entering frequently-used expressions at each use.
- The 'Check expression' button does a preliminary parsing of
the expression and indicates if there are any syntax errors (in the above
example, this button has been clicked).
- The 'Evaluate' button processes the expression using the X and Y values you entered. If any errors are found (see below), a warming message is shown.
NOTE: This routine will only 'catch'
errors in the basic numeric expression. It may
not detect invalid or meaningless math operations that may be attempted
when data are processed, such as division by zero, or taking the
log or a non-integer exponent of a negative number. If such situations
occur, results may be unpredictable.
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