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The Compleat User RPL Encyclopedia


(“Where”)

 'symb' { name1 'symb1' name2 'symb2' ... }    'symb'
x  { name1 'symb1' name2 'symb2' ... }    x
(x,y)  { name1 'symb1' name2 'symb2' ... }    (x,y)

Not in HP-28

Keyboard Access:
   HP48: [alpha]-RS-[VAR]
         LS-9 NXT
HP49/50: RS-TOOL
         «ALGB» NXT
         93.02 MENU
“Where” function. Substitutes values for names in an expression.

The  function is used primarily in algebraic objects, where its syntax is:

The algebraic expression is displayed in the Equation Writer (and on the stack on the HP49/50 in Textbook Mode) as 
This means “X squared, where X=3”.
The stack syntax for the same algebraic expression is:

   HP48:     
HP49/50:     
The  function enables algebraics to include variable-like substitution information about names. Symbolic functions that delay name evaluation (such as integrals and derivatives) can then extract the substitution information from local variables and include that information in the expression, thus avoiding the problem that would occur if the local variables no longer existed when the local names were finally evaluated.

See also:      

BYTES: 2.5