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<!-- Common Lisp HyperSpec (TM), version 7.0 generated by Kent M. Pitman on Mon, 11-Apr-2005 2:31am EDT -->
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<TITLE>CLHS: Function ADJUST-ARRAY</TITLE>
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<H1><A REV=MADE HREF="http://www.lispworks.com/"><IMG WIDTH=80 HEIGHT=65 ALT="[LISPWORKS]" SRC="../Graphics/LWSmall.gif" ALIGN=Bottom></A><A REL=TOP HREF="../Front/index.htm"><IMG WIDTH=237 HEIGHT=65 ALT="[Common Lisp HyperSpec (TM)]" SRC="../Graphics/CLHS_Sm.gif" ALIGN=Bottom></A> <A REL=PREV HREF="f_mk_ar.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="c_arrays.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="f_adju_1.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<HR>
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<A NAME="adjust-array"><I>Function</I> <B>ADJUST-ARRAY</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>adjust-array</B> <I>array new-dimensions <TT>&key</TT> element-type initial-element initial-contents fill-pointer displaced-to displaced-index-offset</I><P> => <I>adjusted-array</I><P>
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<P>
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<P><B>Arguments and Values:</B><P>
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<P>
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<I>array</I>---an <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A>. <P>
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<I>new-dimensions</I>---a <A REL=DEFINITION HREF="26_glo_v.htm#valid_array_dimension"><I>valid array dimension</I></A> or a <A REL=DEFINITION HREF="26_glo_l.htm#list"><I>list</I></A> of <A REL=DEFINITION HREF="26_glo_v.htm#valid_array_dimension"><I>valid array dimensions</I></A>. <P>
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<I>element-type</I>---a <A REL=DEFINITION HREF="26_glo_t.htm#type_specifier"><I>type specifier</I></A>. <P>
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<I>initial-element</I>---an <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A>. <I>Initial-element</I> must not be supplied if either <I>initial-contents</I> or <I>displaced-to</I> is supplied. <P>
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<I>initial-contents</I>---an <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A>. If <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> has rank greater than zero, then <I>initial-contents</I> is composed of nested <A REL=DEFINITION HREF="26_glo_s.htm#sequence"><I>sequences</I></A>, the depth of which must equal the rank of <I>array</I>. Otherwise, <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> is zero-dimensional and <I>initial-contents</I> supplies the single element. <I>initial-contents</I> must not be supplied if either <I>initial-element</I> or <I>displaced-to</I> is given. <P>
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<I>fill-pointer</I>---a <A REL=DEFINITION HREF="26_glo_v.htm#valid_fill_pointer"><I>valid fill pointer</I></A> for the <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> to be created, or <A REL=DEFINITION HREF="a_t.htm#t"><B>t</B></A>, or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. The default is <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. <P>
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<I>displaced-to</I>---an <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. <I>initial-elements</I> and <I>initial-contents</I> must not be supplied if <I>displaced-to</I> is supplied. <P>
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<I>displaced-index-offset</I>---an <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A> of <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> <TT>(fixnum 0 </TT><I>n</I><TT>)</TT> where <I>n</I> is <TT>(array-total-size </TT><I>displaced-to</I><TT>)</TT>. <I>displaced-index-offset</I> may be supplied only if <I>displaced-to</I> is supplied. <P>
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<I>adjusted-array</I>---an <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A>. <P>
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<P><B>Description:</B><P>
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<P>
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<A REL=DEFINITION HREF="#adjust-array"><B>adjust-array</B></A> changes the dimensions or elements of <I>array</I>. The result is an <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> of the same <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> and rank as <I>array</I>, that is either the modified <I>array</I>, or a newly created <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> to which <I>array</I> can be displaced, and that has the given <I>new-dimensions</I>. <P>
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<I>New-dimensions</I> specify the size of each <A REL=DEFINITION HREF="26_glo_d.htm#dimension"><I>dimension</I></A> of <I>array</I>. <P>
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<I>Element-type</I> specifies the <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> of the <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>elements</I></A> of the resulting <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A>. If <I>element-type</I> is supplied, the consequences are unspecified if the <A REL=DEFINITION HREF="26_glo_u.htm#upgraded_array_element_type"><I>upgraded array element type</I></A> of <I>element-type</I> is not the same as the <A REL=DEFINITION HREF="26_glo_a.htm#actual_array_element_type"><I>actual array element type</I></A> of <I>array</I>. <P>
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If <I>initial-contents</I> is supplied, it is treated as for <A REL=DEFINITION HREF="f_mk_ar.htm#make-array"><B>make-array</B></A>. In this case none of the original contents of <I>array</I> appears in the resulting <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A>. <P>
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If <I>fill-pointer</I> is an <A REL=DEFINITION HREF="26_glo_i.htm#integer"><I>integer</I></A>, it becomes the <A REL=DEFINITION HREF="26_glo_f.htm#fill_pointer"><I>fill pointer</I></A> for the resulting <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A>. If <I>fill-pointer</I> is the symbol <A REL=DEFINITION HREF="a_t.htm#t"><B>t</B></A>, it indicates that the size of the resulting <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> should be used as the <A REL=DEFINITION HREF="26_glo_f.htm#fill_pointer"><I>fill pointer</I></A>. If <I>fill-pointer</I> is <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>, it indicates that the <A REL=DEFINITION HREF="26_glo_f.htm#fill_pointer"><I>fill pointer</I></A> should be left as it is. <P>
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If <I>displaced-to</I> <A REL=DEFINITION HREF="26_glo_n.htm#non-nil"><I>non-nil</I></A>, a <A REL=DEFINITION HREF="26_glo_d.htm#displaced_array"><I>displaced array</I></A> is created. The resulting <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> shares its contents with the <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> given by <I>displaced-to</I>. The resulting <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> cannot contain more elements than the <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> it is displaced to. If <I>displaced-to</I> is not supplied or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>, the resulting <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> is not a <A REL=DEFINITION HREF="26_glo_d.htm#displaced_array"><I>displaced array</I></A>. If array A is created displaced to array B and subsequently array B is given to <A REL=DEFINITION HREF="#adjust-array"><B>adjust-array</B></A>, array A will still be displaced to array B. Although <I>array</I> might be a <A REL=DEFINITION HREF="26_glo_d.htm#displaced_array"><I>displaced array</I></A>, the resulting <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> is not a <A REL=DEFINITION HREF="26_glo_d.htm#displaced_array"><I>displaced array</I></A> unless <I>displaced-to</I> is supplied and not <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. The interaction between <A REL=DEFINITION HREF="#adjust-array"><B>adjust-array</B></A> and displaced <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>arrays</I></A> is as follows given three <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>arrays</I></A>, <TT>A</TT>, <TT>B</TT>, and <TT>C</TT>: <P>
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<P><DL><DT><TT>A</TT> is not displaced before or after the call <P><DD>
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<PRE>
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(adjust-array A ...)
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</PRE>
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</TT> <P>
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The dimensions of <TT>A</TT> are altered, and the contents rearranged as appropriate. Additional elements of <TT>A</TT> are taken from <I>initial-element</I>. The use of <I>initial-contents</I> causes all old contents to be discarded. <P>
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<DT><TT>A</TT> is not displaced before, but is displaced to <TT>C</TT> after the call <P><DD>
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<PRE>
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(adjust-array A ... :displaced-to C)
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</PRE>
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</TT> <P>
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None of the original contents of <TT>A</TT> appears in <TT>A</TT> afterwards; <TT>A</TT> now contains the contents of <TT>C</TT>, without any rearrangement of <TT>C</TT>. <P>
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<DT><TT>A</TT> is displaced to <TT>B</TT> before the call, and is displaced to <TT>C</TT> after the call <P><DD>
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<PRE>
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(adjust-array A ... :displaced-to B)
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(adjust-array A ... :displaced-to C)
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</PRE>
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</TT> <P>
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<TT>B</TT> and <TT>C</TT> might be the same. The contents of <TT>B</TT> do not appear in <TT>A</TT> afterward unless such contents also happen to be in <TT>C</TT> If <I>displaced-index-offset</I> is not supplied in the <A REL=DEFINITION HREF="#adjust-array"><B>adjust-array</B></A> call, it defaults to zero; the old offset into <TT>B</TT> is not retained. <P>
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<DT><TT>A</TT> is displaced to <TT>B</TT> before the call, but not displaced afterward. <P><DD>
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<PRE>
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(adjust-array A ... :displaced-to B)
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(adjust-array A ... :displaced-to nil)
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</PRE>
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</TT> <TT>A</TT> gets a new ``data region,'' and contents of <TT>B</TT> are copied into it as appropriate to maintain the existing old contents; additional elements of <TT>A</TT> are taken from <I>initial-element</I> if supplied. However, the use of <I>initial-contents</I> causes all old contents to be discarded. <P></DL> <P>
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If <I>displaced-index-offset</I> is supplied, it specifies the offset of the resulting <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> from the beginning of the <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> that it is displaced to. If <I>displaced-index-offset</I> is not supplied, the offset is 0. The size of the resulting <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> plus the offset value cannot exceed the size of the <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> that it is displaced to. <P>
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If only <I>new-dimensions</I> and an <I>initial-element</I> argument are supplied, those elements of <I>array</I> that are still in bounds appear in the resulting <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A>. The elements of the resulting <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> that are not in the bounds of <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> are initialized to <I>initial-element</I>; if <I>initial-element</I> is not provided, the consequences of later reading any such new <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>element</I></A> of <I>new-array</I> before it has been initialized are undefined. <P>
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If <I>initial-contents</I> or <I>displaced-to</I> is supplied, then none of the original contents of <I>array</I> appears in the new <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A>. <P>
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<P>
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The consequences are unspecified if <I>array</I> is adjusted to a size smaller than its <A REL=DEFINITION HREF="26_glo_f.htm#fill_pointer"><I>fill pointer</I></A> without supplying the <I>fill-pointer</I> argument so that its <A REL=DEFINITION HREF="f_fill_p.htm#fill-pointer"><I>fill-pointer</I></A> is properly adjusted in the process. <P>
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If <TT>A</TT> is displaced to <TT>B</TT>, the consequences are unspecified if <TT>B</TT> is adjusted in such a way that it no longer has enough elements to satisfy <TT>A</TT>. <P>
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<P>
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If <A REL=DEFINITION HREF="#adjust-array"><B>adjust-array</B></A> is applied to an <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> that is <A REL=DEFINITION HREF="26_glo_a.htm#actually_adjustable"><I>actually adjustable</I></A>, the <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> returned is <A REL=DEFINITION HREF="26_glo_i.htm#identical"><I>identical</I></A> to <I>array</I>. If the <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> returned by <A REL=DEFINITION HREF="#adjust-array"><B>adjust-array</B></A> is <A REL=DEFINITION HREF="26_glo_d.htm#distinct"><I>distinct</I></A> from <I>array</I>, then the argument <I>array</I> is unchanged. <P>
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Note that if an <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> A is displaced to another <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> B, and B is displaced to another <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> C, and B is altered by <A REL=DEFINITION HREF="#adjust-array"><B>adjust-array</B></A>, A must now refer to the adjust contents of B. This means that an implementation cannot collapse the chain to make A refer to C directly and forget that the chain of reference passes through B. However, caching techniques are permitted as long as they preserve the semantics specified here. <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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(adjustable-array-p
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(setq ada (adjust-array
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(make-array '(2 3)
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:adjustable t
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:initial-contents '((a b c) (1 2 3)))
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'(4 6)))) => T
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(array-dimensions ada) => (4 6)
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(aref ada 1 1) => 2
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(setq beta (make-array '(2 3) :adjustable t))
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=> #2A((NIL NIL NIL) (NIL NIL NIL))
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(adjust-array beta '(4 6) :displaced-to ada)
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=> #2A((A B C NIL NIL NIL)
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(1 2 3 NIL NIL NIL)
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(NIL NIL NIL NIL NIL NIL)
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(NIL NIL NIL NIL NIL NIL))
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(array-dimensions beta) => (4 6)
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(aref beta 1 1) => 2
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</PRE>
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</TT> <P>
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Suppose that the 4-by-4 array in <TT>m</TT> looks like this: <P>
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<PRE>
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#2A(( alpha beta gamma delta )
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( epsilon zeta eta theta )
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( iota kappa lambda mu )
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( nu xi omicron pi ))
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</PRE>
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</TT> Then the result of <P>
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<PRE>
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(adjust-array m '(3 5) :initial-element 'baz)
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</PRE>
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</TT> is a 3-by-5 array with contents <P>
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<PRE>
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#2A(( alpha beta gamma delta baz )
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( epsilon zeta eta theta baz )
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( iota kappa lambda mu baz ))
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</PRE>
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</TT> <P>
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<P><B>Affected By:</B> None.
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<P>
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<P><B>Exceptional Situations:</B><P>
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<P>
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An error of <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> <A REL=DEFINITION HREF="e_error.htm#error"><B>error</B></A> is signaled if <I>fill-pointer</I> is supplied and <A REL=DEFINITION HREF="26_glo_n.htm#non-nil"><I>non-nil</I></A> but <I>array</I> has no <A REL=DEFINITION HREF="26_glo_f.htm#fill_pointer"><I>fill pointer</I></A>. <P>
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<P><B>See Also:</B><P>
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<P>
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<A REL=DEFINITION HREF="f_adju_1.htm#adjustable-array-p"><B>adjustable-array-p</B></A>, <A REL=DEFINITION HREF="f_mk_ar.htm#make-array"><B>make-array</B></A>, <B>array-dimension-limit</B>, <B>array-total-size-limit</B>, <A REL=DEFINITION HREF="t_array.htm#array"><B>array</B></A> <P>
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<P><B>Notes:</B> None.
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<P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issues</A>, <I>not part of the specification</I>, apply to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss005.htm">ADJUST-ARRAY-NOT-ADJUSTABLE:IMPLICIT-COPY</A><LI> <A REL=CHILD HREF="../Issues/iss355.htm">UNINITIALIZED-ELEMENTS:CONSEQUENCES-UNDEFINED</A><LI> <A REL=CHILD HREF="../Issues/iss003.htm">ADJUST-ARRAY-DISPLACEMENT</A><LI> <A REL=CHILD HREF="../Issues/iss004.htm">ADJUST-ARRAY-FILL-POINTER</A><LI> <A REL=CHILD HREF="../Issues/iss014.htm">ARRAY-DIMENSION-LIMIT-IMPLICATIONS:ALL-FIXNUM</A><P></UL><HR>
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<A REL=NAVIGATOR HREF="../Front/StartPts.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Starting Points]" SRC="../Graphics/StartPts.gif" ALIGN=Bottom></A><A REL=TOC HREF="../Front/Contents.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Contents]" SRC="../Graphics/Contents.gif" ALIGN=Bottom></A><A REL=INDEX HREF="../Front/X_Master.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Index]" SRC="../Graphics/Index.gif" ALIGN=Bottom></A><A REL=INDEX HREF="../Front/X_Symbol.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Symbols]" SRC="../Graphics/Symbols.gif" ALIGN=Bottom></A><A REL=GLOSSARY HREF="../Body/26_a.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Glossary]" SRC="../Graphics/Glossary.gif" ALIGN=Bottom></A><A HREF="../Front/X3J13Iss.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Issues]" SRC="../Graphics/Issues.gif" ALIGN=Bottom></A><BR>
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<A REL=COPYRIGHT HREF="../Front/Help.htm#Legal"><I>Copyright 1996-2005, LispWorks Ltd. All rights reserved.</I></A><P>
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