Inner Product: Difference between revisions

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12 bytes removed ,  02:08, 7 July 2023
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m (→‎Differences between dialects: -- format each expression on its own line for readability)
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   (3 4⍴5)+.×1 5⍴6  ⍝ works in NARS2000 or APL\360, not in Dyalog APL</syntaxhighlight>
   (3 4⍴5)+.×1 5⍴6  ⍝ works in NARS2000 or APL\360, not in Dyalog APL</syntaxhighlight>
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The <syntaxhighlight lang=apl>⊃⍤0⊢(↓⍺)∘.(⍺⍺/⍵⍵¨)↓(¯1⌽⍳⍴⍴⍵)⍉⍵</syntaxhighlight> line of IP above can be written more directly as <syntaxhighlight lang=apl>⍺(⍺⍺⌿⍵⍵¨⍤¯1)⍤1 99⊢⍵</syntaxhighlight> which uses the more efficient major-cell-at-a-time algorithm (rather than row-by-column). The ISO/IEC 13751:2001(E) inner product, conversely, can only be calculated row-by-column, as computing the results one major cell (of the right argument) at a time relies on each application of the right operand being done between two scalars and producing a scalar result.
The <syntaxhighlight lang=apl>⊃⍤0⊢(↓⍺)∘.(⍺⍺/⍵⍵¨)↓(¯1⌽⍳⍴⍴⍵)⍉⍵</syntaxhighlight> line of IP above can be rewritten as <syntaxhighlight lang=apl>⍺(⍺⍺⌿⍵⍵¨⍤¯1)⍤1 99⊢⍵</syntaxhighlight> which uses the more efficient major-cell-at-a-time algorithm (rather than row-by-column). The ISO/IEC 13751:2001(E) inner product, conversely, can only be calculated row-by-column, as computing the results one major cell (of the right argument) at a time relies on each application of the right operand being done between two scalars and producing a scalar result.


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