Perfect numbers: Difference between revisions
add lambdatalk code
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=={{header|LabVIEW}}==
{{VI solution|LabVIEW_Perfect_numbers.png}}
=={{header|Lambdatalk}}==
===simple & slow===
<syntaxhighlight lang="scheme">
{def perf
{def perf.sum
{lambda {:n :sum :i}
{if {>= :i :n}
then {= :sum :n}
else {perf.sum :n
{if {= {% :n :i} 0}
then {+ :sum :i}
else :sum}
{+ :i 1}} }}}
{lambda {:n}
{perf.sum :n 0 2} }}
-> perf
{S.replace \s by space in
{S.map {lambda {:i} {if {perf :i} then :i else}}
{S.serie 2 1000 2}}}
-> 6 28 496 // 5200ms
</syntaxhighlight>
Too slow (and stackoverflow) to go further.
===improved===
<syntaxhighlight lang="scheme">
{def lt_perfect
{def lt_perfect.sum
{lambda {:n :sum :i}
{if {> :i 1}
then {lt_perfect.sum :n
{if {= {% :n :i} 0}
then {+ :sum :i {floor {/ :n :i}}}
else :sum}
{- :i 1}}
else :sum }}}
{lambda {:n}
{let { {:n :n}
{:sqrt {floor {sqrt :n}}}
{:sum {lt_perfect.sum :n 1 {- {floor {sqrt :n}} 0} }}
{:foo {if {= {* :sqrt :sqrt} :n}
then 0
else {floor {/ :n :sqrt}}}}
} {= :n {if {= {% :n :sqrt} 0}
then {+ :sum :sqrt :foo}
else :sum}} }}}
-> lt_perfect
-> {S.replace \s by space in
{S.map {lambda {:i} {if {lt_perfect :i} then :i else}}
{S.serie 6 10000 2}}}
-> 28 496 8128 // 7500ms
</syntaxhighlight>
===calling javascript===
Following the javascript entry.
<syntaxhighlight lang="scheme">
function js_perfect(n) {
var sum = 1, i, sqrt=Math.floor(Math.sqrt(n));
for (i = sqrt-1; i>1; i--) {
if (n % i == 0)
sum += i + n/i;
}
if(n % sqrt == 0)
sum += sqrt + (sqrt*sqrt == n ? 0 : n/sqrt);
return sum === n;
}
{S.replace \s by space in
{S.map {lambda {:i} {if {js_perfect :i} then :i else}}
{S.serie 2 10000}}}
-> 6 28 496 8128 // 80ms
</syntaxhighlight>
=={{header|Lasso}}==
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