source code
{ The Computer Language Benchmarks Game
http://benchmarksgame.alioth.debian.org
contributed by Ian Osgood
modified by Vincent Snijders
modified by Peter Blackman
}
program spectralnorm;
uses cthreads, cmem, mtprocs;
type
aod = array of double;
td =
record
w1 : ^aod;
w2 : ^aod;
end;
var
n,i : ptrint;
u,v,tmp : aod;
vBv,vv : double;
w : td;
wp : ^td;
function A(i,j : ptrint): double; inline;
begin
A := 1 / ((i+j)*(i+j+1) div 2 + i+1);
end;
procedure mulAv(i : ptrint; Data: Pointer; Item: TMultiThreadProcItem);
var j : ptrint;
q : double;
begin
q := 0;
for j := 0 to n-1 do
q := q + A(i,j) * td(Data^).w1^[j];
td(Data^).w2^[i] := q;
end;
procedure mulAtv(i : ptrint; Data: Pointer; Item: TMultiThreadProcItem);
var j : ptrint;
q : double;
begin
q := 0;
for j := 0 to n-1 do
q := q + A(j,i) * td(Data^).w1^[j];
td(Data^).w2^[i] := q;
end;
procedure mulAtAv (AtA1, AtA2 : aod);
begin
w.w1 := @AtA1;
w.w2 := @tmp;
ProcThreadPool.DoParallel(@mulAv, 0, n-1, wp);
w.w1 := @tmp;
w.w2 := @AtA2;
ProcThreadPool.DoParallel(@mulAtv, 0, n-1, wp);
end;
begin
Val(paramstr(1), n, i);
SetLength(u, n);
SetLength(v, n);
SetLength(tmp, n);
vBv := 0;
vv := 0;
wp := @w;
for i := 0 to n-1 do
u[i] := 1.0;
for i := 1 to 10 do
begin
mulAtAv (u,v);
mulAtAv (v,u);
end;
for i := 0 to n-1 do
begin
vBv := vBv + u[i]*v[i];
vv := vv + v[i]*v[i];
end;
writeln(sqrt(vBv/vv):0:9);
end.