13-24 Using mathematical functions
This result is derived from substituting X=S1 and X=0 into 
the original expression found in step 1. However, 
substituting X=0 will not always evaluate to zero and may 
result in an unwanted constant.
To see this, consider: 
The ‘extra’ constant of 6.4 
results from the 
substitution of   into 
(x –2)
5
/5, and should be 
disregarded if an 
indefinite integral is 
required.
Program constants and physical constants
When you press  , three menus of functions and 
constants become available: 
• the math functions menu (which appears by default)
• the program constants menu, and 
• the physical constants menu.
The math functions menu is described extensively earlier 
in this chapter. 
Program constants
The program constants are numbers that have been 
assigned to various calculator settings to enable you to 
test for or specify such a setting in a program. For 
example, the various display formats are assigned the 
following numbers:
1 Standard 
2 Fixed
3 Scientific
4 Engineering
5 Fraction
6 Mixed fraction
In a program, you could store the constant number of a 
particular format into a variable and then subsequently 
test for that particular format. 
x 2–()
4
x
x( 2 )
5
–
5
-------------------
=d
∫
x 0=
HP 39gs English.book  Page 24  Wednesday, December 7, 2005  11:24 PM