RANK ERROR: Difference between revisions

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A '''RANK ERROR''' is an [[error message]] which indicates that an array had an incorrect [[rank]] for the way it was used. For example, in most APLs, [[Iota]] only accepts a [[vector]] or [[scalar]], so giving it a higher-rank array as [[argument]] results in a RANK ERROR:
A '''RANK ERROR''' is an [[error message]] which indicates that an array had an incorrect [[rank]] for the way it was used. For example, in most APLs, [[Iota]] only accepts a [[vector]] or [[scalar]], so giving it a higher-rank array as [[argument]] results in a RANK ERROR:
<source lang=apl>
<syntaxhighlight lang=apl>
       ⍳2 3⍴⍳6
       ⍳2 3⍴⍳6
RANK ERROR
RANK ERROR
Line 8: Line 8:


A RANK ERROR can be caused when arguments do not [[Conformability|conform]] because they have differing ranks:
A RANK ERROR can be caused when arguments do not [[Conformability|conform]] because they have differing ranks:
<source lang=apl>
<syntaxhighlight lang=apl>
       (2 3⍴2) + ⍳6
       (2 3⍴2) + ⍳6
RANK ERROR: Mismatched left and right argument ranks
RANK ERROR: Mismatched left and right argument ranks
Line 16: Line 16:


It may also be caused when an array's rank is too small for a function. [[Windowed Reduction]] is not defined on scalars:
It may also be caused when an array's rank is too small for a function. [[Windowed Reduction]] is not defined on scalars:
<source lang=apl>
<syntaxhighlight lang=apl>
       2 +/ 0.5
       2 +/ 0.5
RANK ERROR
RANK ERROR
Line 24: Line 24:


A RANK ERROR may be caused when argument ranks are incompatible in some other way. In languages with [[high-rank set functions]] such as [[Dyalog APL]] and [[J]], the right argument rank must be at least the left argument rank minus one. Calling it with a matrix left argument and a scalar right argument, which has a rank two smaller, gives a RANK ERROR:
A RANK ERROR may be caused when argument ranks are incompatible in some other way. In languages with [[high-rank set functions]] such as [[Dyalog APL]] and [[J]], the right argument rank must be at least the left argument rank minus one. Calling it with a matrix left argument and a scalar right argument, which has a rank two smaller, gives a RANK ERROR:
<source lang=apl>
<syntaxhighlight lang=apl>
       (⍳3 4) ⍳ ⊂1 3
       (⍳3 4) ⍳ ⊂1 3
RANK ERROR
RANK ERROR

Revision as of 21:09, 10 September 2022

A RANK ERROR is an error message which indicates that an array had an incorrect rank for the way it was used. For example, in most APLs, Iota only accepts a vector or scalar, so giving it a higher-rank array as argument results in a RANK ERROR:

      ⍳2 3⍴⍳6
RANK ERROR
      ⍳2 3⍴⍳6
      ∧

A RANK ERROR can be caused when arguments do not conform because they have differing ranks:

      (2 3⍴2) + ⍳6
RANK ERROR: Mismatched left and right argument ranks
      (2 3⍴2)+⍳6
             ∧

It may also be caused when an array's rank is too small for a function. Windowed Reduction is not defined on scalars:

      2 +/ 0.5
RANK ERROR
      2+/0.5
       ∧

A RANK ERROR may be caused when argument ranks are incompatible in some other way. In languages with high-rank set functions such as Dyalog APL and J, the right argument rank must be at least the left argument rank minus one. Calling it with a matrix left argument and a scalar right argument, which has a rank two smaller, gives a RANK ERROR:

      (⍳3 4) ⍳ ⊂1 3
RANK ERROR
      (⍳3 4)⍳⊂1 3
            ∧
Works in: Dyalog APL


APL features [edit]
Built-ins Primitives (functions, operators) ∙ Quad name
Array model ShapeRankDepthBoundIndex (Indexing) ∙ AxisRavelRavel orderElementScalarVectorMatrixSimple scalarSimple arrayNested arrayCellMajor cellSubarrayEmpty arrayPrototype
Data types Number (Boolean, Complex number) ∙ Character (String) ∙ BoxNamespaceFunction array
Concepts and paradigms Conformability (Scalar extension, Leading axis agreement) ∙ Scalar function (Pervasion) ∙ Identity elementComplex floorArray ordering (Total) ∙ Tacit programming (Function composition, Close composition) ∙ GlyphLeading axis theoryMajor cell searchFirst-class function
Errors LIMIT ERRORRANK ERRORSYNTAX ERRORDOMAIN ERRORLENGTH ERRORINDEX ERRORVALUE ERROREVOLUTION ERROR