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+ entropy test for random

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git-svn-id: trunk@35260 -
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florian 2017-01-08 10:26:12 +00:00
parent d5f2c58d32
commit 1bea9e36eb
2 changed files with 42 additions and 0 deletions
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1
.gitattributes vendored
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@ -13405,6 +13405,7 @@ tests/test/units/system/tres5.rc svneol=native#text/plain
tests/test/units/system/tresb.rc svneol=native#text/plain
tests/test/units/system/tresb.res -text
tests/test/units/system/tresext.pp svneol=native#text/plain
tests/test/units/system/trnd1.pp svneol=native#text/pascal
tests/test/units/system/tround.pp svneol=native#text/plain
tests/test/units/system/tseg.pp svneol=native#text/plain
tests/test/units/system/tsetstr.pp svneol=native#text/plain

41
tests/test/units/system/trnd1.pp Normal file
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@ -0,0 +1,41 @@
uses
math;
const
{$if defined(CPU8) or defined(CPU16)}
lg2upperlimit = 14;
{$else}
lg2upperlimit = 22;
{$endif}
var
a : array of word;
i,j : longint;
upperlimit : longint;
histogram : array[0..high(word)] of longint;
entropy : double;
begin
randomize;
for i:=1 to lg2upperlimit do
begin
upperlimit:=1 shl i;
setlength(a,upperlimit);
for j:=0 to upperlimit-1 do
a[j]:=random(high(word)+1);
FillChar(histogram,sizeof(histogram),0);
for j:=0 to upperlimit-1 do
inc(histogram[a[j]]);
entropy:=0;
for j:=low(histogram) to high(histogram) do
if histogram[j]/upperlimit>0 then
entropy:=entropy-histogram[j]/upperlimit*log2(histogram[j]/upperlimit);
write(entropy);
if entropy<0.9*min(i,16) then
begin
writeln(' Entropy for ',upperlimit,' numbers too low, this could be a spurious result, but if it is happening regularily, random is broken!');
halt(1);
end
else
writeln;
end;
writeln('ok');
end.