
// Make newform 1520.2.d.j in Magma, downloaded from the LMFDB on 25 April 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_1520_d();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_1520_d_Hecke();"
// To make the coeffs of the qexp of the newform in the Hecke field type "qexpCoeffs();"
// To make the newform (type ModFrm), type "MakeNewformModFrm_1520_2_d_j();".
// This may take a long time!  To see verbose output, uncomment the SetVerbose lines below.
// The precision argument determines an initial guess on how many Fourier coefficients to use.
// This guess is increased enough to uniquely determine the newform.
// To make the Hecke irreducible modular symbols subspace (type ModSym)
// containing the newform, type "MakeNewformModSym_1520_2_d_j();".
// This may take a long time!  To see verbose output, uncomment the SetVerbose line below.
// The default sign is -1.  You can change this with the optional parameter "sign".
function ConvertToHeckeField(input: pass_field := false, Kf := [])
    if not pass_field then
        poly := [8, -20, 25, -4, 0, 0, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rf_num := [[1, 0, 0, 0, 0, 0], [0, 1, 0, 0, 0, 0], [-100, 121, -10, 25, 2, 5], [-223, 0, 14, -35, -27, -7], [258, -605, 50, -4, -10, -25], [416, -968, 211, 17, -18, -45]];
    Rf_basisdens := [1, 1, 121, 121, 121, 121];
    Rf_basisnums := ChangeUniverse([[z : z in elt] : elt in Rf_num], Kf);
    Rfbasis := [Rf_basisnums[i]/Rf_basisdens[i] : i in [1..Degree(Kf)]];
    inp_vec := Vector(Rfbasis)*ChangeRing(Transpose(Matrix([[elt : elt in row] : row in input])),Kf);
    return Eltseq(inp_vec);
end function;


// To make the character of type GrpDrchElt, type "MakeCharacter_1520_d();"
function MakeCharacter_1520_d()
    N := 1520;
    order := 2;
    char_gens := [191, 1141, 1217, 401];
    v := [2, 2, 1, 2];
    // chi(gens[i]) = zeta^v[i]
    assert UnitGenerators(DirichletGroup(N)) eq char_gens;
    F := CyclotomicField(order);
    chi := DirichletCharacterFromValuesOnUnitGenerators(DirichletGroup(N,F),[F|F.1^e:e in v]);
    return MinimalBaseRingCharacter(chi);
end function;

// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_1520_d_Hecke();"
function MakeCharacter_1520_d_Hecke(Kf)
    N := 1520;
    order := 2;
    char_gens := [191, 1141, 1217, 401];
    char_values := [[1, 0, 0, 0, 0, 0], [1, 0, 0, 0, 0, 0], [-1, 0, 0, 0, 0, 0], [1, 0, 0, 0, 0, 0]];
    assert UnitGenerators(DirichletGroup(N)) eq char_gens;
    values := ConvertToHeckeField(char_values : pass_field := true, Kf := Kf); // the value of chi on the gens as elements in the Hecke field
    F := Universe(values);// the Hecke field
    chi := DirichletCharacterFromValuesOnUnitGenerators(DirichletGroup(N,F),values);
    return chi;
end function;


function ExtendMultiplicatively(weight, aps, character)
    prec := NextPrime(NthPrime(#aps)) - 1; // we will able to figure out a_0 ... a_prec
    primes := PrimesUpTo(prec);
    prime_powers := primes;
    assert #primes eq #aps;
    log_prec := Floor(Log(prec)/Log(2)); // prec < 2^(log_prec+1)
    F := Universe(aps);
    FXY<X, Y> := PolynomialRing(F, 2);
    // 1/(1 - a_p T + p^(weight - 1) * char(p) T^2) = 1 + a_p T + a_{p^2} T^2 + ...
    R<T> := PowerSeriesRing(FXY : Precision := log_prec + 1);
    recursion := Coefficients(1/(1 - X*T + Y*T^2));
    coeffs := [F!0: i in [1..(prec+1)]];
    coeffs[1] := 1; //a_1
    for i := 1 to #primes do
        p := primes[i];
        coeffs[p] := aps[i];
        b := p^(weight - 1) * F!character(p);
        r := 2;
        p_power := p * p;
        //deals with powers of p
        while p_power le prec do
            Append(~prime_powers, p_power);
            coeffs[p_power] := Evaluate(recursion[r + 1], [aps[i], b]);
            p_power *:= p;
            r +:= 1;
        end while;    
    end for;
    Sort(~prime_powers);
    for pp in prime_powers do
        for k := 1 to Floor(prec/pp) do
            if GCD(k, pp) eq 1 then
                coeffs[pp*k] := coeffs[pp]*coeffs[k];
            end if;
        end for;
    end for;
    return coeffs;
end function;


function qexpCoeffs()
    // To make the coeffs of the qexp of the newform in the Hecke field type "qexpCoeffs();"
    weight := 2;
    raw_aps := [[0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 1], [0, 0, 1, 1, 0, 0], [0, 0, 0, 0, -1, 1], [0, 1, -1, 0, 0, 0], [0, 1, 1, 0, -1, -1], [0, 1, 1, 0, 0, -1], [1, 0, 0, 0, 0, 0], [0, 2, 2, 0, 1, -3], [3, 3, -3, -1, 0, 0], [-2, -3, 3, 2, 0, 0], [0, 0, 0, 0, 3, -2], [0, 1, -1, 2, 0, 0], [0, -1, -1, 0, 3, 0], [0, 2, 2, 0, 3, -2], [0, -1, -1, 0, -3, 1], [1, 2, -2, -1, 0, 0], [-10, -1, 1, 0, 0, 0], [0, -2, -2, 0, 0, -1], [4, -1, 1, -4, 0, 0], [0, 3, 3, 0, 0, -5], [-2, 0, 0, 6, 0, 0], [0, -2, -2, 0, -1, 0], [4, -1, 1, 2, 0, 0], [0, 4, 4, 0, 3, -4], [-2, 5, -5, -8, 0, 0], [0, 3, 3, 0, 2, -4], [0, 0, 0, 0, 2, -3], [9, -1, 1, -3, 0, 0], [0, -5, -5, 0, 3, 0], [0, 4, 4, 0, -4, -2], [-4, 4, -4, 0, 0, 0], [0, -3, -3, 0, -4, 3], [0, -4, 4, -4, 0, 0], [8, -2, 2, -6, 0, 0], [10, 4, -4, -2, 0, 0], [0, 2, 2, 0, 0, 6], [0, -5, -5, 0, -1, 4], [0, 5, 5, 0, 0, -2], [0, 4, 4, 0, 3, -2], [10, -2, 2, -2, 0, 0], [4, 0, 0, -6, 0, 0], [-15, 0, 0, -1, 0, 0], [0, -4, -4, 0, -3, 0], [0, 1, 1, 0, -4, -4], [-1, -4, 4, 9, 0, 0], [3, -6, 6, 9, 0, 0], [0, 0, 0, 0, -4, -2], [0, -2, -2, 0, 2, -7], [-10, 4, -4, 4, 0, 0], [0, 4, 4, 0, 0, -8], [1, 0, 0, 7, 0, 0], [4, -2, 2, 2, 0, 0], [-8, -3, 3, 0, 0, 0], [0, -5, -5, 0, -5, 2], [0, -4, -4, 0, -7, 4], [14, -4, 4, 4, 0, 0], [5, -6, 6, 3, 0, 0], [0, 0, 0, 0, 12, -4], [8, -5, 5, 2, 0, 0], [0, 6, 6, 0, -1, -4], [0, 5, 5, 0, -3, 3], [0, -4, -4, 0, -10, 0], [11, 6, -6, -3, 0, 0], [0, 3, 3, 0, 6, -3], [0, 11, 11, 0, 5, -11], [-13, -4, 4, 9, 0, 0], [0, -9, -9, 0, 1, 6], [0, -2, -2, 0, -5, 4], [6, -4, 4, 8, 0, 0], [0, -3, -3, 0, -4, 5], [7, 4, -4, -7, 0, 0], [0, -4, -4, 0, -1, -2], [0, -3, -3, 0, 1, 5], [3, 0, 0, 1, 0, 0], [0, -1, -1, 0, 8, 0], [-6, -3, 3, 0, 0, 0], [0, -8, -8, 0, -12, 12], [0, -5, 5, 6, 0, 0], [0, 9, -9, -6, 0, 0], [18, -1, 1, -10, 0, 0], [-13, -9, 9, 11, 0, 0], [-20, -1, 1, 8, 0, 0], [0, -1, -1, 0, -1, 0], [-6, -5, 5, -2, 0, 0], [0, 3, 3, 0, 1, 14], [22, -4, 4, 0, 0, 0], [0, 1, 1, 0, 10, -1], [-8, -1, 1, -6, 0, 0], [0, 4, 4, 0, 5, -6], [0, -1, -1, 0, -3, -10], [8, 6, -6, -8, 0, 0], [0, -4, -4, 0, -10, 10], [-2, -3, 3, 2, 0, 0], [10, 1, -1, 6, 0, 0], [0, 2, 2, 0, 1, 7], [0, -2, 2, -2, 0, 0], [-8, -6, 6, -6, 0, 0], [0, -6, -6, 0, -2, 5], [6, -3, 3, 0, 0, 0], [0, -2, -2, 0, -6, 2], [0, 0, 0, 0, 16, 4], [0, -8, -8, 0, -6, 8], [4, 6, -6, -6, 0, 0], [-14, 9, -9, -10, 0, 0], [0, 7, 7, 0, -2, -3], [0, 7, 7, 0, 9, 0], [0, -2, -2, 0, -8, 14], [-22, -3, 3, -2, 0, 0], [28, 1, -1, -2, 0, 0], [0, -4, -4, 0, -14, 2], [0, -7, -7, 0, 6, 2], [0, -2, -2, 0, -14, 0], [0, -3, 3, -8, 0, 0], [2, 14, -14, -18, 0, 0], [-10, 5, -5, -4, 0, 0], [0, 10, 10, 0, 3, -8], [0, 4, 4, 0, 1, 3], [0, 8, 8, 0, 0, 0], [13, 2, -2, 3, 0, 0], [-9, -1, 1, 7, 0, 0], [0, 2, 2, 0, 3, -6], [0, 7, 7, 0, 3, -13], [0, 8, 8, 0, 10, -8], [2, -4, 4, -6, 0, 0], [-20, 2, -2, -2, 0, 0], [-2, -4, 4, -8, 0, 0], [-5, -12, 12, 13, 0, 0], [0, 6, 6, 0, 3, 11], [0, -8, -8, 0, -2, 4], [-6, -3, 3, -10, 0, 0], [0, 11, 11, 0, 0, -2], [-6, -7, 7, 10, 0, 0], [0, -14, -14, 0, 2, -2], [-7, 9, -9, 1, 0, 0], [-23, -5, 5, 9, 0, 0], [0, 13, 13, 0, -9, -3], [0, 2, 2, 0, 2, -9], [0, -11, -11, 0, -13, 19], [-5, 13, -13, 3, 0, 0], [-3, 2, -2, -5, 0, 0], [-20, 10, -10, -14, 0, 0], [0, -4, -4, 0, -13, 17], [0, 4, 4, 0, 20, -9], [-9, -5, 5, 7, 0, 0], [4, -8, 8, 0, 0, 0], [0, 6, 6, 0, 14, -6], [0, 10, 10, 0, 1, -6], [-8, 1, -1, 0, 0, 0], [0, -3, -3, 0, -16, 8], [0, 3, 3, 0, 11, -15], [-4, 6, -6, -6, 0, 0], [0, -18, -18, 0, 9, 8], [0, -5, -5, 0, -10, 8], [0, -10, -10, 0, -2, 19], [16, -4, 4, -8, 0, 0], [5, 8, -8, 3, 0, 0], [21, 3, -3, -15, 0, 0], [0, 11, 11, 0, 0, -11], [-17, 3, -3, -5, 0, 0], [0, 6, 6, 0, -1, -2], [0, -9, -9, 0, -3, 20], [0, 4, 4, 0, 21, -2], [-4, 0, 0, -4, 0, 0], [0, -15, -15, 0, 3, -2], [0, -4, -4, 0, -10, -2], [-2, -13, 13, 22, 0, 0], [0, -5, -5, 0, -10, -8], [20, 10, -10, -10, 0, 0], [0, -5, -5, 0, 2, 8], [-11, 12, -12, -25, 0, 0], [9, -9, 9, 25, 0, 0], [10, 6, -6, -10, 0, 0], [0, -7, -7, 0, -10, 15], [-6, 3, -3, -14, 0, 0], [16, 16, -16, -2, 0, 0], [30, 15, -15, -6, 0, 0], [-38, 0, 0, 0, 0, 0], [0, 13, 13, 0, 4, -10], [-8, -1, 1, -2, 0, 0], [0, 0, 0, 0, 1, -15], [1, 6, -6, 7, 0, 0], [0, 0, 0, 0, -7, 10], [0, -10, -10, 0, 5, 2], [0, 12, 12, 0, 17, -21], [18, -8, 8, -12, 0, 0], [0, -9, -9, 0, 3, 15], [0, -10, -10, 0, 2, 0], [-22, 15, -15, -24, 0, 0], [-5, -14, 14, 5, 0, 0], [0, -1, -1, 0, -3, -4], [0, -6, -6, 0, -5, -6], [4, 2, -2, 4, 0, 0], [-33, -5, 5, 15, 0, 0], [0, -14, -14, 0, 1, 2], [0, 7, 7, 0, -1, -14], [13, 3, -3, -15, 0, 0], [0, -16, -16, 0, -10, 12], [0, 1, 1, 0, -10, 19], [0, -10, -10, 0, 11, 3], [0, -10, 10, -10, 0, 0], [12, 4, -4, 12, 0, 0], [0, -3, -3, 0, 17, -5], [-16, 3, -3, 6, 0, 0], [-2, 0, 0, 6, 0, 0], [0, -12, -12, 0, -8, 12], [-23, 6, -6, 15, 0, 0], [0, 16, 16, 0, 0, -7], [-7, -13, 13, 13, 0, 0], [-13, 2, -2, 5, 0, 0], [0, -1, -1, 0, -2, 11], [-4, -6, 6, 22, 0, 0], [0, 0, 0, 0, -7, 2], [0, -10, -10, 0, -4, 15], [34, 11, -11, -6, 0, 0], [-2, -1, 1, -4, 0, 0], [0, -2, -2, 0, 7, -17], [10, -8, 8, 8, 0, 0], [0, -4, -4, 0, -20, -10], [0, -6, -6, 0, 2, -14], [8, 6, -6, -22, 0, 0], [22, -12, 12, 2, 0, 0], [-2, -7, 7, 24, 0, 0], [0, -10, -10, 0, -11, -1], [0, -12, -12, 0, -2, 15], [-2, -16, 16, 0, 0, 0], [0, -8, -8, 0, 15, 8], [28, 1, -1, -8, 0, 0], [0, -5, -5, 0, -2, -16], [-34, 4, -4, -10, 0, 0], [0, -11, -11, 0, -12, 18], [-3, -14, 14, 15, 0, 0], [-12, -8, 8, 12, 0, 0], [22, -8, 8, -8, 0, 0], [0, 2, 2, 0, -13, 4], [0, 2, 2, 0, -5, 7], [-8, 14, -14, -2, 0, 0], [0, 5, 5, 0, -16, -8], [-10, 16, -16, 6, 0, 0], [-14, -11, 11, 10, 0, 0], [0, 8, 8, 0, 2, -24], [44, 9, -9, -4, 0, 0], [0, 12, 12, 0, 15, -5], [1, 1, -1, -7, 0, 0], [0, -11, -11, 0, -17, 18], [-8, -6, 6, 8, 0, 0], [0, -8, -8, 0, 19, 0], [-8, 18, -18, -4, 0, 0], [-16, 6, -6, 4, 0, 0], [0, 0, 0, 0, 15, 1], [0, 11, 11, 0, -4, 6], [57, -5, 5, 5, 0, 0], [0, 12, 12, 0, -15, -3], [-22, 11, -11, -8, 0, 0], [0, -5, -5, 0, 12, -12], [40, -9, 9, 16, 0, 0], [18, 12, -12, 4, 0, 0], [0, 16, 16, 0, 8, -4], [0, 8, 8, 0, 5, -22], [0, 2, 2, 0, -6, -16], [0, -3, -3, 0, 2, 14], [0, 8, 8, 0, 12, -12], [-8, -1, 1, -2, 0, 0], [0, -19, -19, 0, 13, 7], [0, 14, 14, 0, -12, -4], [-7, -10, 10, -9, 0, 0], [31, 15, -15, -13, 0, 0], [1, -7, 7, 1, 0, 0], [0, 8, 8, 0, -8, -19], [0, -5, -5, 0, 0, -6], [39, 9, -9, 3, 0, 0], [0, -8, -8, 0, 0, 7], [0, -3, -3, 0, 20, 3], [5, 14, -14, -21, 0, 0], [0, 5, 5, 0, 5, -8], [0, -4, -4, 0, 3, -1], [0, 25, 25, 0, -1, -14], [1, 5, -5, 17, 0, 0], [8, 26, -26, -2, 0, 0], [24, 8, -8, -20, 0, 0], [0, -16, -16, 0, 2, -2], [-13, -4, 4, -11, 0, 0], [0, 2, 2, 0, 13, -17], [11, -5, 5, 23, 0, 0], [0, 2, 2, 0, 27, 6], [-20, 14, -14, -12, 0, 0], [0, 15, 15, 0, 2, -7], [0, -4, -4, 0, 11, -4], [-51, -2, 2, 11, 0, 0], [-18, -12, 12, -8, 0, 0], [-38, 1, -1, 16, 0, 0], [0, -14, -14, 0, 1, 22], [0, -3, -3, 0, 11, 0], [-4, -20, 20, 16, 0, 0], [0, -6, -6, 0, 7, -14], [0, -9, 9, 6, 0, 0], [-6, 16, -16, -22, 0, 0], [0, -6, -6, 0, 30, 2], [-13, -2, 2, 17, 0, 0], [0, 15, 15, 0, -9, 10], [0, -2, -2, 0, 30, 0], [0, -3, -3, 0, -9, 3], [-37, 8, -8, -11, 0, 0]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_1520_d_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_1520_2_d_j();".
// This may take a long time!  To see verbose output, uncomment the SetVerbose lines below.
// The precision argument determines an initial guess on how many Fourier coefficients to use.
// This guess is increased enough to uniquely determine the newform.
function MakeNewformModFrm_1520_2_d_j(:prec:=6)
    chi := MakeCharacter_1520_d();
    f_vec := qexpCoeffs();
    Kf := Universe(f_vec);
    // SetVerbose("ModularForms", true);
    // SetVerbose("ModularSymbols", true);
    S := CuspidalSubspace(ModularForms(chi, 2));
    S := BaseChange(S, Kf);
    maxprec := NextPrime(1999) - 1;
    while true do
        trunc_vec := Vector(Kf, [0] cat [f_vec[i]: i in [1..prec]]);
        B := Basis(S, prec + 1);
        S_basismat := Matrix([AbsEltseq(g): g in B]);
        if Rank(S_basismat) eq Min(NumberOfRows(S_basismat), NumberOfColumns(S_basismat)) then
            S_basismat := ChangeRing(S_basismat,Kf);
            f_lincom := Solution(S_basismat,trunc_vec);
            f := &+[f_lincom[i]*Basis(S)[i] : i in [1..#Basis(S)]];
            return f;
        end if;
        error if prec eq maxprec, "Unable to distinguish newform within newspace";
        prec := Min(Ceiling(1.25 * prec), maxprec);
    end while;
end function;


// To make the Hecke irreducible modular symbols subspace (type ModSym)
// containing the newform, type "MakeNewformModSym_1520_2_d_j();".
// This may take a long time!  To see verbose output, uncomment the SetVerbose line below.
// The default sign is -1.  You can change this with the optional parameter "sign".
function MakeNewformModSym_1520_2_d_j( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_1520_d();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<3,R![64, 0, 57, 0, 14, 0, 1]>,<7,R![4, 0, 17, 0, 18, 0, 1]>],Snew);
    return Vf;
end function;