RANK ERROR: Difference between revisions

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Miraheze>Marshall
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Miraheze>Adám Brudzewsky
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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 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 results in a RANK ERROR:
<pre class=apl>
<source=apl>
       ⍳2 3⍴⍳6
       ⍳2 3⍴⍳6
RANK ERROR
RANK ERROR
       ⍳2 3⍴⍳6
       ⍳2 3⍴⍳6
       ∧
       ∧
</pre>
</source>


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:
<pre class=apl>
<source=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
       (2 3⍴2)+⍳6
       (2 3⍴2)+⍳6
             ∧
             ∧
</pre>
</source>


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:
<pre class=apl>
<source=apl>
       2 +/ 0.5
       2 +/ 0.5
RANK ERROR
RANK ERROR
       2+/0.5
       2+/0.5
       ∧
       ∧
</pre>
</source>


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:
<pre class=apl>
<source=apl>
       (⍳3 4) ⍳ ⊂1 3
       (⍳3 4) ⍳ ⊂1 3
RANK ERROR
RANK ERROR
       (⍳3 4)⍳⊂1 3
       (⍳3 4)⍳⊂1 3
             ∧
             ∧
</pre>
</source>
{{Works in|[[Dyalog APL]]}}
{{Works in|[[Dyalog APL]]}}

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