13-20 Using mathematical functions
ACSC Arc cosecant.
ACSC(value)
ASEC Arc secant.
ASEC(value)
COT Cotangent:  cosx/sinx. 
COT(value)
CSC Cosecant:  1/sinx
CSC(value)
SEC Secant:  1/cosx.
SEC(value)
Symbolic calculations
The HP 39gs has the ability to perform symbolic 
calculations, for example, symbolic integration and 
differentiation. You can perform symbolic calculations in 
HOME and in the Function aplet. 
In HOME When you perform calculations that contain normal 
variables, the calculator substitutes values for any 
variables. For example, if you enter A+B on the command 
line and press  , the calculator retrieves the values 
for A and B from memory and substitutes them in the 
calculation.
Using formal 
variables
To perform symbolic calculations, for example symbolic 
differentiations and integrations, you need to use formal 
names. The HP 39gs has six formal names available for 
use in symbolic calculations. These are S0 to S5. When 
you perform a calculation that contains a formal name, 
the HP 39gs does not carry out any substitutions. 
You can mix formal names and real variables. Evaluating 
(A+B+S1)
2
 will evaluate A+B, but not S1.
If you need to evaluate an expression that contains formal 
names numerically, you use the | (where) command, 
listed in the Math menu under the Symbolic category. 
For example to evaluate (S1*S2)
2
 
when
 
S1=2 and 
S2=4, you would enter the calculation as follows:
HP 39gs English.book  Page 20  Wednesday, December 7, 2005  11:24 PM