Factorial: Difference between revisions
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=={{header|Phix}}==
{{libheader|Phix/basics}}
standard iterative factorial builtin, reproduced below. returns inf for 171 and above, and is not accurate above 22 on 32-bit, or 25 on 64-bit.
<!--<lang Phix>
<span style="color: #008080;">global</span> <span style="color: #008080;">function</span> <span style="color: #000000;">factorial<span style="color: #0000FF;">(<span style="color: #004080;">integer</span> <span style="color: #000000;">n<span style="color: #0000FF;">)</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">1</span>
<span style="color: #008080;">while</span> <span style="color: #000000;">n<span style="color: #0000FF;">><span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
<span style="color: #000000;">res</span> <span style="color: #0000FF;">*=</span> <span style="color: #000000;">n</span>
<span style="color: #000000;">n</span> <span style="color: #0000FF;">-=</span> <span style="color: #000000;">1</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #008080;">return</span> <span style="color: #000000;">res</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function
<!--</lang>-->
=== gmp ===
{{libheader|Phix/mpfr}}
For seriously big numbers, with perfect accuracy, use the mpz_fac_ui() routine. For a bit of fun, we'll see just how far we can push it, in ten seconds or less.
<!--<lang Phix>
<span style="color: #008080;">include</span> <span style="color: #000000;">mpfr<span style="color: #0000FF;">.<span style="color: #000000;">e</span>
<span style="color: #7060A8;">mpz</span> <span style="color: #000000;">f</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">mpz_init<span style="color: #0000FF;">(<span style="color: #0000FF;">)</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">n</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">2</span>
<span style="color: #004080;">bool</span> <span style="color: #000000;">still_running</span> <span style="color: #0000FF;">=</span> <span style="color: #004600;">true<span style="color: #0000FF;">,</span>
<span style="color: #000000;">still_printing</span> <span style="color: #0000FF;">=</span> <span style="color: #004600;">true</span>
<span style="color: #008080;">while</span> <span style="color: #000000;">still_running</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">t0</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">time<span style="color: #0000FF;">(<span style="color: #0000FF;">)</span>
<span style="color: #7060A8;">mpz_fac_ui<span style="color: #0000FF;">(<span style="color: #000000;">f<span style="color: #0000FF;">,</span> <span style="color: #000000;">n<span style="color: #0000FF;">)</span>
<span style="color: #000000;">still_running</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">(<span style="color: #7060A8;">time<span style="color: #0000FF;">(<span style="color: #0000FF;">)<span style="color: #0000FF;">-<span style="color: #000000;">t0<span style="color: #0000FF;">)<span style="color: #0000FF;"><<span style="color: #000000;">10</span> <span style="color: #000080;font-style:italic;">-- (stop once over 10s)</span>
<span style="color: #004080;">string</span> <span style="color: #000000;">ct</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">elapsed<span style="color: #0000FF;">(<span style="color: #7060A8;">time<span style="color: #0000FF;">(<span style="color: #0000FF;">)<span style="color: #0000FF;">-<span style="color: #000000;">t0<span style="color: #0000FF;">)<span style="color: #0000FF;">,</span> <span style="color: #000000;">res<span style="color: #0000FF;">,</span> <span style="color: #000000;">what<span style="color: #0000FF;">,</span> <span style="color: #000000;">pt</span>
<span style="color: #000000;">t0</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">time<span style="color: #0000FF;">(<span style="color: #0000FF;">)</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">still_printing</span> <span style="color: #008080;">then</span>
<span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">shorten<span style="color: #0000FF;">(<span style="color: #7060A8;">mpz_get_str<span style="color: #0000FF;">(<span style="color: #000000;">f<span style="color: #0000FF;">)<span style="color: #0000FF;">)</span>
<span style="color: #000000;">what</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"printed"</span>
<span style="color: #000000;">still_printing</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">(<span style="color: #7060A8;">time<span style="color: #0000FF;">(<span style="color: #0000FF;">)<span style="color: #0000FF;">-<span style="color: #000000;">t0<span style="color: #0000FF;">)<span style="color: #0000FF;"><<span style="color: #000000;">10</span> <span style="color: #000080;font-style:italic;">-- (stop once over 10s)</span>
<span style="color: #008080;">else</span>
<span style="color: #000000;">res</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">sprintf<span style="color: #0000FF;">(<span style="color: #008000;">"%,d digits"<span style="color: #0000FF;">,<span style="color: #7060A8;">mpz_sizeinbase<span style="color: #0000FF;">(<span style="color: #000000;">f<span style="color: #0000FF;">,<span style="color: #000000;">10<span style="color: #0000FF;">)<span style="color: #0000FF;">)</span>
<span style="color: #000000;">what</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"size in base"</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000000;">pt</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">elapsed<span style="color: #0000FF;">(<span style="color: #7060A8;">time<span style="color: #0000FF;">(<span style="color: #0000FF;">)<span style="color: #0000FF;">-<span style="color: #000000;">t0<span style="color: #0000FF;">)</span>
<span style="color: #7060A8;">printf<span style="color: #0000FF;">(<span style="color: #000000;">1<span style="color: #0000FF;">,<span style="color: #008000;">"factorial(%d):%s, calculated in %s, %s in %s\n"<span style="color: #0000FF;">,</span>
<span style="color: #0000FF;">{<span style="color: #000000;">n<span style="color: #0000FF;">,<span style="color: #000000;">res<span style="color: #0000FF;">,<span style="color: #000000;">ct<span style="color: #0000FF;">,<span style="color: #000000;">what<span style="color: #0000FF;">,<span style="color: #000000;">pt<span style="color: #0000FF;">}<span style="color: #0000FF;">)</span>
<span style="color: #000000;">n</span> <span style="color: #0000FF;">*=</span> <span style="color: #000000;">2</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while
<!--</lang>-->
{{out}}
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