Reference Guide

3-136 Full Command and Function Reference
Input/Output:
Level 1/Argument 1 Level 1/Item 1
z
→
ln z
'symb'
→
'LN(symb)'
See also: ALOG, EXP, ISOL, LNP1, LOG
LNAME
Type: Command
Description: Returns the variable names contained in a symbolic expression.
Access: Catalog, …µ
Input: A symbolic expression.
Output: Level 2/Argument 1: The original expression.
Level 1/Argument 2: A vector containing the variable names. The variable names are sorted by
length, longest first, and ones of equal length are sorted alphabetically.
Flags: Exact mode must be set (flag –105 clear).
Numeric mode must not be set (flag –3 clear).
Example: List the variables in the expression COS(B)/2*A + MYFUNC(PQ) + 1/T.
Command: LNAME(COS(B)/2*A + MYFUNC(PQ) + INV(T))
Result: {COS(B)/2*A + MYFUNC(PQ) + 1/T, [MYFUNC,PQ,A,B,T]}
See also: LVAR
LNCOLLECT
Type: Command
Description: Simplifies an expression by collecting logarithmic terms. For symbolic powers does not perform
the same simplification as EXP2POW; compare example 2 here with example 2 for EXP2POW.
Access: Algebra, …× , !Ð, or PL EXP & LN , or !Ú REWRITE L
Input: An expression.
Output: The simplified expression.
Flags: Exact mode must be set (flag –105 clear).
Numeric mode must not be set (flag –3 clear).
Radians mode must be set (flag –17 set).
Example 1: Simplify the following expression:
2(ln(x)+ln(y))
Command: LNCOLLECT(2(LN(X)+LN(Y))
Result: LN(X^2*Y)
Example 2: Compare the effect of LNCOLLECT with the effect of EXP2POW on the expression e
n·ln(x)
Command: LNCOLLECT(EXP(N*LN(X))
Result: EXP(N*LN(X))
See also: EXP2POW, TEXPAND
LNP1
Type: Analytic function
Description: Natural Log of x Plus 1 Analytic Function: Returns ln(x + 1).
For values of x close to zero, LNP1(x) returns a more accurate result than does LN(x+1). Using
LNP1 allows both the argument and the result to be near zero, and it avoids an intermediate
result near 1. The calculator can express numbers within 10
-449
of zero, but within only 10
–11
of 1.
For values of x < –1, an Undefined Result error results. For x=–1, an Infinite Result exception
occurs, or, if flag –22 is set, LNP1 returns –MAXR.
Access: !´ HYPERBOLIC LNP 1 ( ´ is the left-shift of the Pkey).