
// Make newform 675.2.e.c in Magma, downloaded from the LMFDB on 25 April 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_675_e();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_675_e_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_675_2_e_c();".
// 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_675_2_e_c();".
// 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 := [9, 15, 37, -8, 23, -2, 8, -2, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rf_num := [[1, 0, 0, 0, 0, 0, 0, 0], [0, 1, 0, 0, 0, 0, 0, 0], [-2934, -741, -1691, -3496, -722, -361, -32, -76], [-968, -117, -267, 133, -114, -57, 31, -12], [2988, -29793, 9047, -10043, 4694, -3818, 1079, -263], [2016, -10371, 6104, -6776, 1013, -2576, 728, -326], [-1116, 4261, -3379, 3751, -1258, 1426, -403, 156], [17217, 4758, 10858, 10118, 4636, 2318, -119, 488]];
    Rf_basisdens := [1, 1, 6165, 685, 6165, 6165, 2055, 6165];
    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_675_e();"
function MakeCharacter_675_e()
    N := 675;
    order := 3;
    char_gens := [326, 352];
    v := [1, 3];
    // 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_675_e_Hecke();"
function MakeCharacter_675_e_Hecke(Kf)
    N := 675;
    order := 3;
    char_gens := [326, 352];
    char_values := [[-1, 0, 0, 0, 0, 1, 0, 0], [1, 0, 0, 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, -1, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, -1, 0, 0, 0], [0, 0, 0, 0, -1, -1, 2, 0], [0, 1, -1, 2, 0, 0, -2, 0], [2, 0, 0, 2, 0, 0, 0, -1], [0, 0, 2, -1, 0, 0, 0, 0], [-5, -1, 1, 1, -1, 5, -1, 1], [0, -2, 0, 0, -1, 2, -1, 0], [1, -1, 1, -2, -2, -1, 2, 2], [3, 0, -4, -1, 0, 0, 0, -1], [-1, -1, 1, -1, 1, 1, 1, -1], [0, -2, 0, 0, 2, -1, -2, 0], [0, 0, 0, 0, -2, -5, 1, 0], [6, 0, 1, -3, 0, 0, 0, 0], [3, -1, 1, 0, -3, -3, 0, 3], [0, 2, 0, 0, 1, 1, 2, 0], [3, -3, 3, 0, 1, -3, 0, -1], [3, 0, 1, -3, 0, 0, 0, 0], [-1, 0, 3, -3, 0, 0, 0, 2], [0, 0, 0, 0, 1, 3, -3, 0], [0, 3, 0, 0, 0, -9, 0, 0], [0, 0, 3, 0, 0, 0, 0, 3], [0, 2, 0, 0, -1, -5, -1, 0], [0, 5, 0, 0, 2, -1, -4, 0], [0, 2, -2, -2, -1, 0, 2, 1], [7, 0, -5, -2, 0, 0, 0, 1], [-5, 0, -1, -1, 0, 0, 0, 2], [-5, -6, 6, 1, -1, 5, -1, 1], [-2, 0, -1, 2, 0, 0, 0, -2], [-6, -3, 3, 0, -3, 6, 0, 3], [0, 1, 0, 0, 4, -5, 1, 0], [-8, -6, 6, 3, 0, 8, -3, 0], [-7, -4, 4, -1, 1, 7, 1, -1], [0, 5, 0, 0, 1, 1, -7, 0], [3, 5, -5, 1, 2, -3, -1, -2], [-1, 0, 4, 7, 0, 0, 0, -2], [-8, 5, -5, 1, -1, 8, -1, 1], [0, -5, 0, 0, -5, 1, 4, 0], [0, 0, 2, -6, 0, 0, 0, 0], [-3, 0, -5, 4, 0, 0, 0, -2], [0, -10, 0, 0, 0, 9, 0, 0], [-5, -2, 2, -1, -2, 5, 1, 2], [2, 0, 5, 2, 0, 0, 0, -1], [5, 0, -2, 1, 0, 0, 0, 5], [-4, -7, 7, 1, -4, 4, -1, 4], [0, 6, 0, 0, 0, -1, 3, 0], [0, 0, 0, 0, -1, -10, -1, 0], [7, -1, 1, -5, 1, -7, 5, -1], [-4, 0, -1, -1, 0, 0, 0, 2], [-7, 3, -3, -7, -5, 7, 7, 5], [0, 7, 0, 0, 0, -9, 4, 0], [3, 0, 0, -3, 0, 0, 0, -6], [-3, 0, 0, -6, 3, 3, 6, -3], [0, 0, 0, 0, 8, -4, -7, 0], [10, 0, 0, 4, 0, 0, 0, -2], [12, 0, -1, -7, 0, 0, 0, 0], [0, 5, 0, 0, 1, -10, 11, 0], [0, 4, 0, 0, 1, 4, 1, 0], [0, 0, 0, 3, 7, 0, -3, -7], [10, 5, -5, -5, 2, -10, 5, -2], [18, 0, 4, -8, 0, 0, 0, 3], [14, -11, 11, -7, -2, -14, 7, 2], [0, -1, 0, 0, 5, -11, -1, 0], [0, 5, 0, 0, 7, -5, -2, 0], [0, -4, 0, 0, -6, 11, -1, 0], [13, 3, -3, -6, -1, -13, 6, 1], [2, -4, 4, -13, -2, -2, 13, 2], [0, -6, 0, 0, -7, 8, 6, 0], [0, 1, 0, 0, -2, 16, -5, 0], [5, 0, -7, -1, 0, 0, 0, -4], [0, 5, 0, 0, -2, -10, 2, 0], [0, -2, 2, -4, -6, 0, 4, 6], [-10, 0, 4, -5, 0, 0, 0, -1], [-5, -1, 1, 4, 8, 5, -4, -8], [0, 4, 0, 0, 1, -23, 7, 0], [-2, 0, -1, -1, 0, 0, 0, 7], [14, 7, -7, 5, 7, -14, -5, -7], [-13, 5, -5, 1, 5, 13, -1, -5], [8, -4, 4, 5, 4, -8, -5, -4], [0, -7, 0, 0, 1, 1, -1, 0], [8, 0, -7, 8, 0, 0, 0, -1], [-1, 0, -3, 6, 0, 0, 0, -1], [0, -10, 0, 0, -2, -2, 8, 0], [0, 5, 0, 0, 2, -4, 5, 0], [15, 0, 2, -3, 0, 0, 0, 6], [0, -6, 0, 0, 1, 25, -6, 0], [0, -7, 0, 0, 8, 14, 5, 0], [5, 13, -13, 8, 5, -5, -8, -5], [2, 0, 10, -4, 0, 0, 0, 2], [0, 14, 0, 0, -4, -13, 2, 0], [-17, 0, 6, 0, 0, 0, 0, 6], [4, 9, -9, -11, -4, -4, 11, 4], [17, 9, -9, -6, -2, -17, 6, 2], [6, 0, 2, 15, 0, 0, 0, -3], [-2, 13, -13, 4, 8, 2, -4, -8], [-27, 0, 10, 3, 0, 0, 0, 6], [24, 0, -11, -2, 0, 0, 0, 0], [7, 0, -5, 7, 0, 0, 0, -6], [0, 3, 0, 0, -2, -5, -12, 0], [-8, 0, 7, -5, 0, 0, 0, 7], [-10, 13, -13, 8, 4, 10, -8, -4], [0, -5, 0, 0, 7, -8, -8, 0], [16, 0, 0, 6, 3, -16, -6, -3], [18, 0, -10, 5, 0, 0, 0, -10], [0, -5, 0, 0, -5, 10, -8, 0], [-9, 0, 5, 3, 0, 0, 0, -9], [-7, -4, 4, -1, 1, 7, 1, -1], [0, -2, 0, 0, 10, -4, 1, 0], [8, 14, -14, -2, -8, -8, 2, 8], [-6, 0, 4, 1, 0, 0, 0, -9], [2, 1, -1, 14, 4, -2, -14, -4], [0, -5, 0, 0, -5, 8, -11, 0], [-18, 0, 17, 2, 0, 0, 0, 6], [0, 14, 0, 0, 8, 14, -13, 0], [15, -3, 3, -3, 1, -15, 3, -1], [32, 0, -6, -1, 0, 0, 0, 2], [20, -6, 6, -10, 1, -20, 10, -1], [0, -11, 0, 0, 0, 27, -6, 0], [-19, 9, -9, 0, 4, 19, 0, -4], [0, 8, 0, 0, 1, 29, -10, 0], [0, 3, 0, 0, 9, 0, -15, 0], [6, 0, -9, 3, 0, 0, 0, -3], [0, -11, 0, 0, 6, 6, 1, 0], [-2, 0, -7, -11, 0, 0, 0, 1], [0, -5, 0, 0, -9, -12, 7, 0], [-15, 0, 6, 18, 0, 0, 0, -3], [0, -9, 0, 0, 0, 20, -15, 0], [5, -21, 21, -9, 0, -5, 9, 0], [15, 0, -10, -1, 0, 0, 0, 3], [-15, -2, 2, 6, 3, 15, -6, -3], [-14, -2, 2, -7, 2, 14, 7, -2], [-17, 0, 20, 5, 0, 0, 0, -5], [4, -1, 1, 13, 8, -4, -13, -8], [27, 4, -4, 8, 10, -27, -8, -10], [11, 0, -10, -7, 0, 0, 0, -4], [-17, 0, 0, 9, -4, 17, -9, 4], [7, 4, -4, -5, -10, -7, 5, 10], [-15, 0, 16, 0, 0, 0, 0, 6], [22, 0, 4, -8, 0, 0, 0, 3], [0, 4, 0, 0, 4, 4, 10, 0], [-15, -1, 1, -11, -1, 15, 11, 1], [-8, 0, -7, 13, 0, 0, 0, -11], [20, 0, -10, -7, 0, 0, 0, 1], [0, -5, 0, 0, -7, 2, 5, 0], [0, 6, 0, 0, -4, -6, 6, 0], [0, -10, 0, 0, -12, -15, 6, 0], [7, 7, -7, -16, -4, -7, 16, 4], [21, 0, 2, 0, 0, 0, 0, 12], [18, 9, -9, 3, 7, -18, -3, -7], [18, 0, 2, 9, 0, 0, 0, 0], [-11, 0, -18, 9, 0, 0, 0, 0], [-18, -18, 18, -3, -6, 18, 3, 6], [0, -13, 0, 0, -5, -10, 17, 0], [0, -1, 0, 0, -5, -11, 13, 0], [-10, 0, -2, 7, 0, 0, 0, 2], [0, 10, 0, 0, 5, -13, -4, 0], [3, 0, 15, 0, 0, 0, 0, -5], [29, 5, -5, -10, -5, -29, 10, 5], [0, 8, 0, 0, -7, 5, 17, 0], [1, 0, -4, -14, 0, 0, 0, 13], [23, 9, -9, 0, 3, -23, 0, -3], [23, 0, 2, 8, 0, 0, 0, -7], [22, 15, -15, -5, 11, -22, 5, -11], [0, -3, 0, 0, 3, -24, -3, 0], [-3, 0, 1, -2, 0, 0, 0, -8], [0, 1, 0, 0, -3, 40, 1, 0]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_675_e_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_675_2_e_c();".
// 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_675_2_e_c(:prec:=8)
    chi := MakeCharacter_675_e();
    f_vec := qexpCoeffs();
    Kf := Universe(f_vec);
    // SetVerbose("ModularForms", true);
    // SetVerbose("ModularSymbols", true);
    S := CuspidalSubspace(ModularForms(chi, 2));
    S := BaseChange(S, Kf);
    maxprec := NextPrime(997) - 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_675_2_e_c();".
// 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_675_2_e_c( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_675_e();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<2,R![9, -15, 37, 8, 23, 2, 8, 2, 1]>],Snew);
    return Vf;
end function;