manual:chapter6:operators:cmd_ovr_eval [newRPL User Manual]

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Evaluate an object, recursively

Input Stack		Output Stack
O₁	→	see list under Description
Level 1	→	Level n	…	Level 1

Legend

Legend	Object type
O	Any object
I	Integer number
R	Real number
#	Binary number
Num	Scalar (Integer, Real or Binary number)
Z	Complex number
U	Unit
∡	Angle
A	Symbolic expression
C	Symbolic constant
V	Vector
M	Matrix
S	String
1/0	Any expression evaluating to True or False
G	Grob
F	Font
D	Binary data container
T	Tag object
L	List
cL	Case list
N	Variable name / Identifier
Dir	Directory
pDir	Packed Directory
P	Program
Lib	Library

Type	Operator
Parallel list processing	Yes, but specific group is determined by the object being evaluated
Affected by flags	-70	Global autosimplification rules
	-71	Application of Group 1 autosimplification rules
	-72	Application of Group 2 autosimplification rules
	-73	Application of Group 3 autosimplification rules
	-74	Application of Group 4 autosimplification rules
	-75	Application of Group 5 autosimplification rules
	-76	Application of Group 6 autosimplification rules
	-77	Application of Group 7 autosimplification rules
	-78	Application of Group 8 autosimplification rules
	-103	Complex results

The EVAL command evaluates the object on the top level of the stack. Evaluation occurs recursively.

The effect of the evaluation and the resulting output depends on the type of object being evaluated, as summarized by the following list.

Local Name: EVAL recalls the content of the variable.
Global Name: EVAL calls the content of a variable:
1. a Name is evaluated;
2. a Program is evaluated;
3. a Directory becomes the current directory;
4. other objects which are not lists are put on the stack.
Program: EVAL enters each object in the program:
1. an unquoted Name is evaluated;
2. a Keyword is XEQted;
3. other objects which are not lists are put on the stack.
Symbolic expression: EVAL enters each object in the expression:
1. a Name is evaluated;
2. a Keyword is XEQted;
3. other objects which are not lists are put on the stack.
Other objects: if they are not lists EVAL puts them on the stack.
List: EVAL enters each object in the list:
1. any object is evaluated according above mentioned rules.

As a final step, EVAL will perform numerical simplification according to the status of flags from -70 to -78.

This command is only partially compatible with userRPL.

In particular:

In userRPL, if the argument is a list EVAL enters any object in the list, then:
1. a Name is evaluated;
2. a Program is evaluated;
3. a Keyword is XEQted;
4. other objects are put on the stack.

while in newRPL, parallel list processing is performed.

If the following commands are executed

2:                          6.28
1:                       'TWOPI'
……………………………………………………………………………………
STO

2:                   « TWOPI * »
1:                      'CIRCUM'
……………………………………………………………………………………
STO

then the command

2:                             2
1:                      'CIRCUM'
……………………………………………………………………………………
EVAL

will perform the following steps:

Resulting in

1:                         12.56
……………………………………………………………………………………

The command

1:                    { '16' √ }
……………………………………………………………………………………
EVAL

will perform the following steps:

Resulting in

1:                        { 4. }
……………………………………………………………………………………

Overloadable operators 26 3 NEW

Operator	Short Description
Evaluation operators:
EVAL1	Evaluate one level	NEW
EVAL	Evaluate full depth
XEQ	Execute	NEW
→NUM	Compute numeric result
Test operators:
==	Equality test
≠	Not equal test
<	Less than test
≤	Less than or equal test
>	Greater than test
≥	Greater than or equal test
CMP	Comparison test (<0 if A<B, 0 if A==B, >0 if A>B)	NEW
SAME	Comparison test, true if objects are the same
ISTRUE	True test	NEW
Logical operators:
AND	Logical AND
OR	Logical OR
XOR	Logical XOR
NOT	Logical NOT
Mathematic operators:
+	Addition
-	Subtraction
*	Multiplication
/	Division
^	Power
XROOT	Root
INV	Inverse
NEG	Negate/change sign
ABS	Magnitude or absolute value