HP 50g User's Reference Manual
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Brand: HP
Category: Calculator
Type: Advanced user's reference manual
Model: HP 48gII , HP 49g+ , HP 50G
Pages: 693
3-174 Full Command and Function Reference
POS
Type: Command
Description: Position Command: Returns the position of a substring within a string or the position of an
object within a list.
If there is no match for obj or substring, POS returns zero.
Access: !°L
CHARS POS
( °is the left-shift of the Nkey).
!°
LIST ELEM POS
( °is the left-shift of the Nkey).
@& N
POS
Input/Output:
Level 2/Argument 1 Level 1/Argument 2 Level 1/Item 1
“string”
“substring”
→
n
{ list }
obj
→
n
See also: CHR, NUM, REPL, SIZE, SUB
POTENTIAL
Type: Command
Description: Find the potential field function describing a field whose vector gradient is input. This command
is the opposite of DERIV. Given a vector V it attempts to return a function U such that grad U
is equal to V;
VU =∇
. For this to be possible, CURL(V) must be zero, otherwise the command
reports a “Bad Argument Value” error. Step-by-step mode is available with this command.
Access: Catalog, …µ
Input: Level 2/Argument 1: A vector V of expressions.
Level 1/Argument 2: A vector of the names of the variables.
Output: Level 1/Item 1: A function U of the variables that is the potential from which V is derived. An
arbitrary constant can be added, the command does not do this.
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).
Step-by-step mode can be set (flag –100 set).
Example: To confirm that this command is the opposite of DERIV, use the output of the example in
DERIV, and show that the result is the same as the input given in the DERIV example. Find the
function of the spatial variables x, y, and z whose gradient is:
(4xy+z)
i
+ (2x
2
+ 6yz)
j
+ (x+3y
2
)
k
Command:
POTENTIAL([4*X*Y+Z, 2*X^2+6*Y*Z, X+3*Y^2], [X,Y,Z])
EXPAND(ANS(1))
Result:
2*Y*X^2+Z*X+3*Z*Y^2
See also: DERIV, VPOTENTIAL
POWEXPAND
Type: Function
Description: Rewrites an expression raised to a power as a product. If followed by repeated execution of
DISTRIB allows an expression to be expanded fully, step by step.
Access: !Ú
REWRITE
L
Input: An expression raised to a power.