Strand Assignment: Difference between revisions
From NARS2000
Jump to navigationJump to search
Sudleyplace (talk | contribs) No edit summary |
Sudleyplace (talk | contribs) No edit summary |
||
| Line 4: | Line 4: | ||
<table border="0" cellpadding="5" cellspacing="0" summary=""> | <table border="0" cellpadding="5" cellspacing="0" summary=""> | ||
<tr> | <tr> | ||
<td><apl size="large"> (A<sub>1</sub> A<sub>2</sub> ... A<sub>n</sub>) | <td><apl size="large"> (A<sub>1</sub> A<sub>2</sub> ... A<sub>n</sub>)←R</apl></td> | ||
<td></td> | <td></td> | ||
<td></td> | <td></td> | ||
| Line 17: | Line 17: | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>If <apl size="large">1< | <td>If <apl size="large">1<⍴⍴R</apl>, signal a <apl size="large">RANK ERROR</apl>.</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>If <apl size="large">R</apl> is a scalar or one element vector, its item is assigned to each name, as in <apl size="large">A<sub>i</sub> | <td>If <apl size="large">R</apl> is a scalar or one element vector, its item is assigned to each name, as in <apl size="large">A<sub>i</sub>←⊃⍬⍴R</apl>.</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
| Line 26: | Line 26: | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>If <apl size="large"> | <td>If <apl size="large">n≠⍴R</apl>, signal a <apl size="large">LENGTH ERROR</apl>.</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>Otherwise, each successive item of <apl size="large">R</apl> is assigned to each successive name, as in <apl size="large">A<sub>i</sub> | <td>Otherwise, each successive item of <apl size="large">R</apl> is assigned to each successive name, as in <apl size="large">A<sub>i</sub>←i⊃R</apl>.</td> | ||
</tr> | </tr> | ||
</table> | </table> | ||
<br /> | <br /> | ||
<br /> | <br /> | ||
For example, <apl size="large">(A B C) | For example, <apl size="large">(A B C)←{enclose}{iota}3</apl> is shorthand for <apl size="large">A{is}B{is}C{is}{iota}3</apl>. In contrast, <apl size="large">(A B C)←{iota}3</apl> is shorthand for <apl size="large">A←1 {diamond} B←2 {diamond} C←3</apl>. | ||
Note that <apl size="large">(A B) | Note that <apl size="large">(A B)←B A</apl> is a simple and efficient way to swap the values of the two names. | ||
Revision as of 15:51, 9 April 2008
|
||||
| A1 A2 ... An are assignable names, R is a scalar or vector. | ||||
| If 1<⍴⍴R, signal a RANK ERROR. | ||||
| If R is a scalar or one element vector, its item is assigned to each name, as in Ai←⊃⍬⍴R. | ||||
| Otherwise, assume there are n names in the list: | ||||
| If n≠⍴R, signal a LENGTH ERROR. | ||||
| Otherwise, each successive item of R is assigned to each successive name, as in Ai←i⊃R. |
For example, (A B C)←⊂⍳3 is shorthand for A←B←C←⍳3. In contrast, (A B C)←⍳3 is shorthand for A←1 ⋄ B←2 ⋄ C←3.
Note that (A B)←B A is a simple and efficient way to swap the values of the two names.
