alglattices

default(realprecision,38);
default(parisize,"100M");

\\Tests for lattices, orders and makeintegral in algebras

Sn(n) = [Vecsmall(numtoperm(n,i)) | i <- [0..n!-1]];
D2n(n)=
{
  [[vectorsmall(2*n,i,if(i==n,1,i==2*n,n+1,i+1)),
    vectorsmall(2*n,i,if(i==1,n+1,i==n+1,1,2*n+2-i))],Vecsmall([n,2])];
}
firstprime1mod(n) =
{
  p = 2;
  while(p%n!=1, p=nextprime(p+1));
  p;
}

al = alginit(nfinit(y^2+7), [-1,-1]);
a = [1,1,-1/2,1,1/3,-1,1,1]~;
mt = algtomatrix(al,a,1);
lat = alglathnf(al,mt);
print(type(lat)=="t_VEC");
print(#lat == 2);
print(type(lat[1])=="t_MAT");
print(type(lat[2])=="t_FRAC");
print(type(lat[1][1,1])=="t_INT");
print(lat[1][2,1]==0);
c = [1,1,-1,1,0,-1,1,1]~;
mt = algtomatrix(al,c,1);
lat = alglathnf(al,mt);
print(lat[2]==1);
print(lat == alglathnf(al,c))
lat = alglathnf(al,matid(8)*2);
print(lat[2]==2);
b = [1,0,-1,1,0,-1,2,1]~;
mtb = algtomatrix(al,b,1);
lat = alglathnf(al,matconcat([mt,mtb]));
print(lat==[1,1]);
print(lat == alglathnf(al,[mt,mtb]));
lat = alglathnf(al,matconcat([7*mt/2,7*mtb/2]),21/2);
print(lat==[1,7/2]);
lat1 = alglathnf(al,a);
lat2 = alglathnf(al,c);
N = algdim(al,1);
lat3 = [11*matid(N),1];
lat4 = [3*matid(N),1];
print(alglatinter(al,lat3,lat4) == [matid(N),33]);
print(alglatadd(al,lat3,lat4) == [matid(N),1]);
print(alglatadd(al,lat1,alglatadd(al,lat2,lat3)) ==
  alglatadd(al,alglatadd(al,lat1,lat2),lat3));
print(alglatinter(al,lat1,alglatinter(al,lat2,lat3)) ==
  alglatinter(al,alglatinter(al,lat1,lat2),lat3));
{print(alglatinter(al, alglatadd(al,lat1,lat2), lat3) == alglatadd(al,
  alglatinter(al,lat1,lat3),alglatinter(al,lat2,lat3)));}
inter1 = alglatinter(al,lat1,lat2,&sum1);
sum2 = alglatadd(al,lat1,lat2,&inter2);
print(inter1==inter2);
print(sum1==sum2);
print(sum1[2]==1/6);
print(inter1[2]==1);
print(alglatindex(al,lat1,lat2));
print(alglatmul(al,lat1,lat2));
print(alglatmul(al,b,lat1));
print(alglatmul(al,lat2,b));
print(alglatmul(al,b/10,lat1));
print(alglatmul(al,lat2,b/10));
print(alglatlefttransporter(al,lat1,lat2));
print(alglatrighttransporter(al,lat1,lat2));
setrand(88);
aa = algrandom(al,10);
print(alglathnf(al,aa/10,matdet(algtomatrix(al,aa,1))/10)==alglathnf(al,aa/10));
print(alglatcontains(al,lat1,a));
col = [3,6,-5,1,23,2,0,1]~;
print(alglatelement(al,lat1,col));
testlataddinter()=
{
  my(lat=[0,0,0],int12,int23,sum12,index,elt1,
  elt2,tr12L,tr23R,col1,col2);
  my(lat=[0,0,0],int12,int23,sum12,index,elt,tr12L,tr23R);
  elt1=algrandom(al,5)/random([1,8]);
  elt2=algrandom(al,5)/random([1,8]);
  elt=algrandom(al,5);
  for(i=1,3,lat[i]=alglathnf(al,algrandom(al,2)/random([1,8])));
  sum12 = alglatadd(al,lat[1],lat[2],&int12);
  if(alglatadd(al,lat[1],alglatadd(al,lat[2],lat[3],&int23))
    != alglatadd(al,sum12,lat[3]),
    print("error (add)",lat);
    return(0)
  );
  if(alglatinter(al,lat[1],int23) != alglatinter(al,int12,lat[3]),
    print("error (inter)",lat);
    return(0)
  );
  if(!alglatsubset(al,lat[1],sum12,&index) ||
      (index!=alglatindex(al,lat[1],sum12)),
    print("error (subset/index)",lat);
    return(0)
  );
  if(alglatsubset(al,lat[1],lat[2]) != (lat[2]==sum12),
    print("error (subset)",lat);
    return(0)
  );
  if(alglatindex(al,lat[2],lat[3])*alglatindex(al,lat[3],lat[2])!=1,
    print("error (index)", lat);
    return(0)
  );
  if(alglatmul(al,lat[1],alglatmul(al,lat[2],lat[3])) !=
    alglatmul(al,alglatmul(al,lat[1],lat[2]),lat[3]),
    print("error (latmul)", lat);
    return(0)
  );
  if((alglatmul(al,elt1,alglatmul(al,elt2,lat1)) !=
      alglatmul(al,algmul(al,elt1,elt2),lat1)) ||
     (alglatmul(al,alglatmul(al,lat2,elt1),elt2) !=
      alglatmul(al,lat2,algmul(al,elt1,elt2))),
    print("error (latmul elt)", lat, elt1, elt2);
    return(0)
  );
  tr12L = alglatlefttransporter(al,lat[1],lat[2]);
  tr12L = tr12L[1]*tr12L[2];
  for(i=1,8,
    if(!alglatsubset(al,alglatmul(al,tr12L[,i],lat[1]),lat[2]),
      print("error (left transporter)", lat, i);
      return(0)
    )
  );
  tr23R = alglatrighttransporter(al,lat[2],lat[3]);
  tr23R = tr23R[1]*tr23R[2];
  for(i=1,8,
    if(!alglatsubset(al,alglatmul(al,lat[2],tr23R[,i]),lat[3]),
      print("error (right transporter)", lat, i);
      return(0)
    )
  );
  for(i=1,5,
    col1 = [random([-10,10]) | j <- [1..8]]~;
    if(!alglatcontains(al,lat1,alglatelement(al,lat1,col1),&col2) || col1!=col2,
      print("error (latelement)", lat, col1);
      return(0)
    );
    if(alglatcontains(al,lat1,col1,&col2) && col1!=alglatelement(al,lat1,col2),
      print("error (latcontains)", lat, col1);
      return(0)
    )
  );
  1
};
setrand(1);
nb = 250;
for(i=1,nb,if(!testlataddinter(),print(i);break()));

print("make integral");
mt = [matid(2),[0,-1/4;1,0]];
mt2 = algmakeintegral(mt);
algisassociative(mt2)
al = algtableinit(mt2);
algissimple(al)
{mt = [matid(4), [0,-1,0,0;1,0,0,0;0,0,0,-3;0,0,1/3,0],
[0,0,2/9,0;0,0,0,-2/3;1,0,0,0;0,-1/3,0,0],
[0,0,0,2;0,0,2/3,0;0,3,0,0;1,0,0,0]];}
mt2 = algmakeintegral(mt);
algisassociative(mt2)
al = algtableinit(mt2);
algissimple(al)
mt = algmultable(alginit(nfinit(y),[-3,7]));
mt == algmakeintegral(mt)

print("integral subalg");
m = matcompanion(x^4+1);
mt = [m^i | i <- [0..3]];
al = algtableinit(mt);
B = [1,0;0,0;0,1/2;0,0]
al2 = algsubalg(al,B);
algisassociative(al2[1])
al2[2]

print("bug in subalg when first vector is not 1");
mt = [matid(3), [0,0,0; 1,1,0; 0,0,0], [0,0,1; 0,0,0; 1,0,1]];
A = algtableinit(mt,2);
B = algsubalg(A,[0,1; 0,0; 1,0]);
algissimple(B[1])

print("image of lifts in algsimpledec");
testidem(al)={
  dec = algsimpledec(al,1)[2];
  Le = [d[3][,1] | d <- dec];
  for(i=1,#Le,
    ei = Le[i];
    if(algsqr(al,ei)!=ei, print(0); return;);
    for(j=i+1,#Le,
      ej = Le[j];
      if(algmul(al,ei,ej)!=0, print(0); return;);
    );
  );
  print(1);
}
{for(n=2,4,
  al = alggroup(Sn(n),7);
  testidem(al);
);}
{for(n=2,5,
  al = alggroupcenter(Sn(n),11);
  testidem(al);
);}
{for(n=2,4,
  p = firstprime1mod(2*n);
  al = alggroup(D2n(n),p);
  testidem(al);
);}
{for(n=2,5,
  al = alggroupcenter(Sn(n),11);
  testidem(al);
);}
/* \\needs galpol package
{for(i=1,267,
  print("i=",i);
  [pol,den] = galoisgetpol(64,i,1);
  gal = galoisinit(pol,den);
  al = alggroupcenter(gal,193);
  testidem(al);
);}*/

print("lattices in al_CSA");
setrand(1);
nf = nfinit(y^2-7);
a = y;
b = y+1;
ab = lift(Mod(a*b,nf.pol));
mti = [0,a,0,0;1,0,0,0;0,0,0,a;0,0,1,0];
mtj = [0,0,b,0;0,0,0,-b;1,0,0,0;0,-1,0,0];
mtk = [0,0,0,-ab;0,0,b,0;0,-a,0,0;1,0,0,0];
mt = [matid(4),mti,mtj,mtk];
al = alginit(nf,mt);
x1 = [0,2/7,7,-1,0,0,1/5,-5]~;
x2 = [-1/7-3*y,y+3/5,y,20+y]~;
lat1 = alglathnf(al,x1);
lat2 = alglathnf(al,x2);
lat3 = alglathnf(al,concat([8/5*matid(8),[1,0,0,1,0,1,1,1]~]));
alglatsubset(al,alglatmul(al,alglatlefttransporter(al,lat1,lat3),lat1),lat3)
alglatadd(al,lat1,alglatadd(al,lat2,lat3))==alglatadd(al,alglatadd(al,lat1,lat2),lat3)
{alglatinter(al,lat1,alglatinter(al,lat2,lat3)) ==
  alglatinter(al,alglatinter(al,lat1,lat2),lat3)}

print("examples from docu")
al = alginit(nfinit(y^2+7), [-1,-1]);
lat1 = alglathnf(al,[1,1,0,0,0,0,0,0]~);
lat2 = alglathnf(al,[1,0,1,0,0,0,0,0]~);
latsum = alglatadd(al,lat1,lat2,&latinter);
matdet(latsum[1])
matdet(latinter[1])
latinter = alglatinter(al,lat1,lat2,&latsum);
matdet(latsum[1])
matdet(latinter[1])
alglatsubset(al,lat1,lat2)
alglatsubset(al,lat1,latsum,&index)
index
alglatindex(al,lat1,lat2)
lat1==lat2
a1 = [1,-1,0,1,2,0,1,2]~;
a2 = [0,1,2,-1,0,0,3,1]~;
lat1 = alglathnf(al,a1);
alglatcontains(al,lat1,a1,&c)
c
c = [1..8]~;
elt = alglatelement(al,lat1,c);
alglatcontains(al,lat1,elt,&c2)
c==c2
lat2 = alglathnf(al,a2);
lat3 = alglatmul(al,lat1,lat2);
matdet(lat3[1])
lat3 == alglathnf(al, algmul(al,a1,a2))
lat3 == alglatmul(al, lat1, a2)
lat3 == alglatmul(al, a1, lat2)
lat1 = alglathnf(al,[1,-1,0,1,2,0,5,2]~);
lat2 = alglathnf(al,[0,1,-2,-1,0,0,3,1]~);
tr = alglatlefttransporter(al,lat1,lat2);
alglatsubset(al,alglatmul(al,tr[1][,7]*tr[2],lat1),lat2)
alglatsubset(al,alglatmul(al,lat1,tr[1][,7]*tr[2]),lat2)
lat1 = alglathnf(al,matdiagonal([1,3,7,1,2,8,5,2]));
lat2 = alglathnf(al,matdiagonal([5,3,8,1,9,8,7,1]));
tr = alglatrighttransporter(al,lat1,lat2);
alglatsubset(al,alglatmul(al,lat1,tr[1][,8]*tr[2]),lat2)
alglatsubset(al,alglatmul(al,tr[1][,8]*tr[2],lat1),lat2)
\\end examples

print("bad inputs");
al = alginit(nfinit(y^2+7), [-1,-1]);
alglathnf(al,0);
alglathnf(al,Mat([0,0,0,0,0,0,0,0]));
alglathnf(al,[0;0;0;0;0;0;0;0]);
fakemat = matid(8);
fakemat[5,6] = []
alglathnf(al,fakemat);
alglathnf(al,matid(8)*0);
fakemat = matid(8);
fakemat[1,1] = 0;
alglathnf(al,fakemat);
lat = alglathnf(al,matconcat([mt*0,mt*0]));
a = [[0,0]~,[0,0]~;[0,0]~,[0,0]~];
lat1 = alglathnf(al,a);
lat2 = alglathnf(al,c);
col = [3,6,-5,1,23,2,0,1]~;
print(alglatelement(al,lat1,col~));
a = [1,1,-1/2,1,1/3,-1,1,1]~;
b = [1,0,-1,1,0,-1,2,1]~;
alglatmul(al,a,b);
mt = [matid(2),[0,-1/4;1/2,0]];
algmakeintegral(mt);
mt = [[1,0;-1,1],[0,-1/4;1,0]];
algmakeintegral(mt);
algmakeintegral('x,1);
alglatmul(al,lat1,[matdiagonal([1,1,0,1,1,1,1,1]),1]);
\\end bad inputs