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Am 8 Feb 2006 um 15:32 hat Stavros Macrakis geschrieben:
> I'm afraid Maxima's system of arrays is rather messy. There are three
> kinds of arrays: named Maxima arrays, anonymous Lisp arrays, and
> lists/matrices used as 1/2-dimensional arrays.
>
> The array function creates a named array and adds it to the 'arrays' list.
>
> The make_array function creates an *anonymous* array, which is not
> added to the 'arrays' list. In your example above, you have not named
> the array, you have assigned an array value to a variable.
>
that makes it clear
> Personally, I prefer the list/matrix solution because they are
> first-class objects in the Maxima world, though they are slower -- but
> that doesn't matter for many applications.
I did time consuming computations with 2-dim-lists, so I am interested to know, if arrays
are faster. let's see ...
>
> > foo works when not compiled, but not when compiled. can someone explain?
>
> I'm not sure, but the compiler probably assumes that array is a named array.
named arrays do not seem be a solution. the compiled function does not see the
values.
(%i1) array(test,2,3);
(%o1) test
(%i2) arrays;
(%o2) [test]
(%i3) for r:0 thru 2 do
for c:0 thru 3 do
test[r,c]: random(10)$
(%i4) printArray(array,rows,cols):= block(
[ row ],
for r:0 thru rows do (
row:[],
for c:cols thru 0 step -1 do row:cons(array[r,c],row),
apply('print,row) ) )$
(%i5) printArray(test,2,3);
2 2 4 5
4 1 9 5
8 3 5 5
(%o5) done
(%i6) compile(printArray);
Compiling gazonk0.lsp.
End of Pass 1.
End of Pass 2.
OPTIMIZE levels: Safety=2, Space=3, Speed=2
Finished compiling gazonk0.lsp.
(%o6) [printArray]
(%i7) printArray(test,2,3);
test test test test
0, 0 0, 1 0, 2 0, 3
test test test test
1, 0 1, 1 1, 2 1, 3
test test test test
2, 0 2, 1 2, 2 2, 3
(%o7) done
Volker
_______________________________________________
> Maxima mailing list
> Maxima at math.utexas.edu
> http://www.math.utexas.edu/mailman/listinfo/maxima
>
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<div align="left"><font face="Arial"><span style="font-size:10pt">Am 8 Feb 2006 um 15:32 hat Stavros Macrakis geschrieben:</span></font></div>
<div align="left"><br/>
</div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> I'm afraid Maxima's system of arrays is rather messy.  There are three</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> kinds of arrays: named Maxima arrays, anonymous Lisp arrays, and</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> lists/matrices used as 1/2-dimensional arrays.</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> </span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> The array function creates a named array and adds it to the 'arrays' list.</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> </span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> The make_array function creates an *anonymous* array, which is not</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> added to the 'arrays' list.  In your example above, you have not named</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> the array, you have assigned an array value to a variable.</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> </span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">that makes it clear</span></font></div>
<div align="left"><br/>
</div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> Personally, I prefer the list/matrix solution because they are</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> first-class objects in the Maxima world, though they are slower -- but</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> that doesn't matter for many applications.</span></font></div>
<div align="left"><br/>
</div>
<div align="left"><font face="Arial"><span style="font-size:10pt">I did time consuming computations with 2-dim-lists, so I am interested to know, if arrays </span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">are faster. let's see ...</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> </span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> > foo works when not compiled, but not when compiled. can someone explain?</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> </span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> I'm not sure, but the compiler probably assumes that array is a named array.</span></font></div>
<div align="left"><br/>
</div>
<div align="left"><font face="Arial"><span style="font-size:10pt">named arrays do not seem be a solution. the compiled function does not see the </span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">values.</span></font></div>
<div align="left"><br/>
</div>
<div align="left"><font face="Arial"><span style="font-size:10pt">(%i1) array(test,2,3);</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">(%o1)                                           
test</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">(%i2) arrays;</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">(%o2)                                          
[test]</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">(%i3) for r:0 thru 2 do</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">            for c:0 thru 3 do</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">                        test[r,c]:
random(10)$</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">(%i4) printArray(array,rows,cols):= block(</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">            [ row ],</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">            for r:0 thru rows do (</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">                        row:[],</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">                        for
c:cols thru 0 step -1 do row:cons(array[r,c],row),</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">                        apply('print,row)
) )$</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">(%i5) printArray(test,2,3);</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">2 2 4 5 </span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">4 1 9 5 </span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">8 3 5 5 </span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">(%o5)                                           
done</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">(%i6) compile(printArray);</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">Compiling gazonk0.lsp.</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">End of Pass 1.  </span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">End of Pass 2.  </span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">OPTIMIZE levels: Safety=2, Space=3, Speed=2</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">Finished compiling gazonk0.lsp.</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">(%o6)                                       
[printArray]</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">(%i7) printArray(test,2,3);</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">test     test          test      
test       </span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">     0, 0      0, 1       0, 2       
0, 3</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">test     test          test      
test       </span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">     1, 0      1, 1       1, 2      
1, 3</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">test     test          test      
test       </span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">     2, 0      2, 1       2, 2      
2, 3</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt">(%o7)                                           
done</span></font></div>
<div align="left"><br/>
</div>
<div align="left"><font face="Arial"><span style="font-size:10pt">Volker</span></font></div>
<div align="left"><font face="Arial"><span style="font-size:10pt"> _______________________________________________</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> Maxima mailing list</span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> </span></font><font face="Arial" color="#008000"><span style="font-size:10pt"><u>Maxima at math.utexas.edu</u></span></font></div>
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> </span></font><font face="Arial" color="#008000"><span style="font-size:10pt"><u>http://www.math.utexas.edu/mailman/listinfo/maxima</u></span></font></div>;
<div align="left"><font face="Arial" color="#7f0000"><span style="font-size:10pt">> </span></font></div>
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