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Diffstat (limited to 'theta_lib/theta_structures/theta_helpers_dim4.py')
-rw-r--r-- | theta_lib/theta_structures/theta_helpers_dim4.py | 259 |
1 files changed, 0 insertions, 259 deletions
diff --git a/theta_lib/theta_structures/theta_helpers_dim4.py b/theta_lib/theta_structures/theta_helpers_dim4.py deleted file mode 100644 index 29599b0..0000000 --- a/theta_lib/theta_structures/theta_helpers_dim4.py +++ /dev/null @@ -1,259 +0,0 @@ -from sage.all import * -import itertools - -## Index management -@cached_function -def index_to_multindex(k): - r""" - Input: - - k: integer between 0 and 15. - - Output: binary decomposition of k. - """ - L_ind=[] - l=k - for i in range(4): - L_ind.append(l%2) - l=l//2 - return tuple(L_ind) - -@cached_function -def multindex_to_index(*args): - r""" - Input: 4 elements i0,i1,i2,i3 in {0,1}. - - Output: k=i0+2*i1+4*i2+8*i3. - """ - if len(args)==4: - i0,i1,i2,i3=args - else: - i0,i1,i2,i3=args[0] - return i0+2*i1+4*i2+8*i3 - -@cached_function -def scal_prod(i,j): - r""" - Input: Two integers i and j in {0,...,15}. - - Output: Scalar product of the bits of i and j mod 2. - """ - return (int(i)&int(j)).bit_count()%2 - -def act_point(P,I,J): - r""" - Input: - - P: a point with 16 coordinates. - - I, J: two 4-tuples of indices in {0,1}. - - Output: the action of (I,\chi_J) on P given by: - (I,\chi_J)*P=(\chi_J(I+K)^{-1}P[I+K])_K - """ - Q=[] - i=multindex_to_index(I) - j=multindex_to_index(J) - for k in range(16): - ipk=i^k - Q.append((-1)**scal_prod(ipk,j)*P[ipk]) - return Q - -## Product of theta points -def product_theta_point_dim4(P0,P1,P2,P3): - # Computes the product theta coordinates of a product of 4 elliptic curves. - P=[0 for k in range(16)] - for i0, i1, i2, i3 in itertools.product([0,1],repeat=4): - P[multindex_to_index(i0,i1,i2,i3)]=P0[i0]*P1[i1]*P2[i2]*P3[i3] - return P - -def product_theta_point_dim2_dim4(P0,P1): - # Computes the product theta coordinates of a product of 2 abelian surfaces. - P=[0 for k in range(16)] - for i0, i1, i2, i3 in itertools.product([0,1],repeat=4): - P[multindex_to_index(i0,i1,i2,i3)]=P0[i0+2*i1]*P1[i2+2*i3] - return P - -## 4-dimensional product Theta point to 1-dimensional Theta points -def product_to_theta_points_dim4(P): - Fp2=P[0].parent() - d_Pi={0:None,1:None,2:None,3:None} - d_index_ratios={0:None,1:None,2:None,3:None}# Index of numertors/denominators to compute the theta points. - for k in range(4): - is_zero=True# theta_1(Pk)=0 - for I in itertools.product([0,1],repeat=3): - J=list(I) - J.insert(k,1) - j=multindex_to_index(*J) - if P[j]!=0: - is_zero=False - d_index_ratios[k]=[j^(2**k),j] - break - if is_zero: - d_Pi[k]=(Fp2(1),Fp2(0)) - L_num=[] - L_denom=[] - d_index_num_denom={} - for k in range(4): - if d_Pi[k]==None:# Point has non-zero coordinate theta_1 - d_index_num_denom[k]=len(L_num) - L_num.append(P[d_index_ratios[k][0]]) - L_denom.append(P[d_index_ratios[k][1]]) - L_denom=batch_inversion(L_denom) - for k in range(4): - if d_Pi[k]==None: - d_Pi[k]=(L_num[d_index_num_denom[k]]*L_denom[d_index_num_denom[k]],Fp2(1)) - return d_Pi[0],d_Pi[1],d_Pi[2],d_Pi[3] - -## 4-dimensional product Theta point to 2-dimensional Theta points -def product_to_theta_points_dim4_dim2(P): - Fp2=P[0].parent() - k0=0# Index of the denominator k0=multindex_to_index(I0,J0) and - # we divide by theta_{I0,J0}=theta_{I0}*theta_{J0}!=0 - while k0<=15 and P[k0]==0: - k0+=1 - i0, j0 = k0%4, k0//4 - inv_theta_k0=1/P[k0] - theta_P1=[] - theta_P2=[] - for i in range(4): - if i==i0: - theta_P1.append(1) - else: - theta_P1.append(P[i+4*j0]*inv_theta_k0) - for j in range(4): - if j==j0: - theta_P2.append(1) - else: - theta_P2.append(P[i0+4*j]*inv_theta_k0) - return theta_P1, theta_P2 - - - - - -## Usual theta transformations -@cached_function -def inv_16(F): - return 1/F(16) - -def hadamard2(x,y): - return (x+y, x-y) - -def hadamard4(x,y,z,t): - x,y=hadamard2(x,y) - z,t=hadamard2(z,t) - return (x+z, y+t, x-z, y-t) - -def hadamard8(a,b,c,d,e,f,g,h): - a,b,c,d=hadamard4(a,b,c,d) - e,f,g,h=hadamard4(e,f,g,h) - return (a+e, b+f, c+g, d+h, a-e, b-f, c-g, d-h) - -def hadamard16(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p): - a,b,c,d,e,f,g,h=hadamard8(a,b,c,d,e,f,g,h) - i,j,k,l,m,n,o,p=hadamard8(i,j,k,l,m,n,o,p) - return (a+i, b+j, c+k, d+l, e+m, f+n, g+o, h+p, a-i, b-j, c-k, d-l, e-m, f-n, g-o, h-p) - -def hadamard_inline(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p): - a,b=a+b,a-b - c,d=c+d,c-d - e,f=e+f,e-f - g,h=g+h,g-h - i,j=i+j,i-j - k,l=k+l,k-l - m,n=m+n,m-n - o,p=o+p,o-p - a,b,c,d=a+c,b+d,a-c,b-d - e,f,g,h=e+g,f+h,e-g,f-h - i,j,k,l=i+k,j+l,i-k,j-l - m,n,o,p=m+o,n+p,m-o,n-p - a,b,c,d,e,f,g,h=a+e, b+f, c+g, d+h, a-e, b-f, c-g, d-h - i,j,k,l,m,n,o,p=i+m,j+n,k+o,l+p,i-m,j-n,k-o,l-p - return (a+i, b+j, c+k, d+l, e+m, f+n, g+o, h+p, a-i, b-j, c-k, d-l, e-m, f-n, g-o, h-p) - -def hadamard(P): - return hadamard16(*P) - #return hadamard_inline(*P) - -def hadamard_inverse(P): - H_inv_P=[] - C=inv_16(P[0].parent()) - for j in range(16): - HP.append(0) - for k in range(16): - if scal_prod(k,j)==0: - H_inv_P[j]+=P[k] - else: - H_inv_P[j]-=P[k] - H_inv_P[j]=H_inv_P[j]*C - return H_inv_P - -def squared(P): - return [x**2 for x in P] - -def batch_inversion(L): - r"""Does n inversions in 3(n-1)M+1I. - - Input: - - L: list of elements to invert. - - Output: - - [1/x for x in L] - """ - # Given L=[a0,...,an] - # Computes multiples=[a0, a0.a1, ..., a0...an] - multiples=[L[0]] - for ai in L[1:]: - multiples.append(multiples[-1]*ai) - - # Computes inverses=[1/(a0...an),...,1/a0] - inverses=[1/multiples[-1]] - for i in range(1,len(L)): - inverses.append(inverses[-1]*L[-i]) - - # Finally computes [1/a0,...,1/an] - result=[inverses[-1]] - for i in range(2,len(L)+1): - result.append(inverses[-i]*multiples[i-2]) - return result - - -## Functions to handle zero theta coordinates -def find_zeros(P): - L_ind_zeros=[] - for i in range(16): - if P[i]==0: - L_ind_zeros.append(i) - return L_ind_zeros - -def find_translates(L_ind_zeros): - L_ind_non_zero=[] - L_ind_origin=L_ind_zeros.copy() - - for i in range(16): - if i not in L_ind_zeros: - L_ind_non_zero.append(i) - - L_trans=[] - while L_ind_origin!=[]: - n_target_max=0 - ind_trans_max=0 - for k in range(16): - trans=[x^k for x in L_ind_origin] - n_target=0 - for y in trans: - if y in L_ind_non_zero: - n_target+=1 - if n_target>n_target_max: - n_target_max=n_target - ind_trans_max=k - L_trans.append(ind_trans_max) - L_ind_remove=[] - for x in L_ind_origin: - if x^ind_trans_max in L_ind_non_zero: - L_ind_remove.append(x) - for x in L_ind_remove: - L_ind_origin.remove(x) - return L_trans - - - - |