Using mathematical functions 13-17
XPON Exponent of value.
XPON(value)
Example
XPON(123.4) returns 2
Two-variable statistics
These are functions for use with two-variable statistics. 
See “Two-variable” on page 10-15.
Symbolic functions
The symbolic functions are used for symbolic 
manipulations of expressions. The variables can be 
formal or numeric, but the result is usually in symbolic 
form (not a number). You will find the symbols for the 
symbolic functions = and | (where) in the CHARS menu 
(
CHARS) as well as the MATH menu. 
= (
equals
) Sets an equality for an equation. This is not a logical 
operator and does not store values. (See “Test functions” 
on page 13-18.)
expression1=expression2
ISOLATE Isolates the first occurrence of variable in expression=0 
and returns a new expression, where 
variable=newexpression. The result is a general solution 
that represents multiple solutions by including the (formal) 
variables S1 to represent any sign and n1 to represent 
any integer.
ISOLATE(expression, variable)
Examples
ISOLATE(2*X+8,X) returns -4
ISOLATE(A+B*X/C,X) returns -(A*C/B)
LINEAR? Tests whether expression is linear for the specified 
variable. Returns 0 (false) or 1 (true). 
LINEAR?(expression, variable)
Example
LINEAR?((X^2-1)/(X+1),X) returns 0
HP 39gs English.book  Page 17  Wednesday, December 7, 2005  11:24 PM