HP 40gs User Manual page 197

hp40g+.book Page 15 Friday, December 9, 2005 1:03 AM
SUBST
TEXPAND
UNASSIGN
Computer Algebra System (CAS)
Substitute a value for a variable
SUBST has two parameters: an expression dependent on
a parameter, and an equality (parameter=substitute
value).
SUBST substitutes the specified value for the variable in
the expression.
Typing:
2
SUBST(A +1,A=2)
gives:
2
2 + 1
Develop in terms of sine and cosine
TEXPAND has a trigonometric expression or
transcendental function as an argument.
TEXPAND develops this expression in terms of sin(x) and
cos(x).
Example
Typing:
TEXPAND(COS(X+Y))
gives:
y ( ) ⋅ x ( )
cos cos – sin
Example
Typing:
TEXPAND(COS(3·X))
gives:
3
⋅ x ( ) ⋅ x ( )
4 cos – 3 cos
Clear a variable
UNASSIGN is used to clear a variable, for example:
UNASSIGN(ABC)
y ( ) ⋅ x ( )
sin
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