
// Make newform 325.2.n.c in Magma, downloaded from the LMFDB on 25 April 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_325_n();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_325_n_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_325_2_n_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_325_2_n_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 := [4, -2, -1, -1, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rf_num := [[1, 0, 0, 0], [0, 1, 0, 0], [-2, -1, 1, 1], [2, 1, 1, -1]];
    Rf_basisdens := [1, 1, 2, 2];
    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_325_n();"
function MakeCharacter_325_n()
    N := 325;
    order := 6;
    char_gens := [27, 301];
    v := [6, 5];
    // 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_325_n_Hecke();"
function MakeCharacter_325_n_Hecke(Kf)
    N := 325;
    order := 6;
    char_gens := [27, 301];
    char_values := [[1, 0, 0, 0], [1, 0, -1, 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 := [[1, 0, 0, -1], [0, 0, -1, 0], [0, 0, 0, 0], [-1, 0, -1, 0], [0, 0, 1, -2], [1, 0, -4, 0], [1, -2, -3, 4], [1, 0, 1, 0], [2, -4, -3, 2], [2, -4, -3, 2], [2, -6, -4, 6], [0, 0, 3, -6], [0, 0, -1, 2], [-7, 2, 9, -4], [0, 4, 0, -4], [2, 2, 0, 2], [3, 4, 7, 0], [5, 2, -3, -4], [-8, 0, 1, 6], [-1, 4, 3, 0], [0, 0, 0, 0], [-6, 0, 0, 0], [-4, -2, 8, 2], [-8, 0, 5, -2], [1, -6, -5, 0], [0, 0, -9, 0], [-8, 4, 0, 4], [-2, 4, 9, -2], [6, -6, -12, 6], [11, 2, -9, -4], [6, -12, -13, 6], [-2, -2, 0, -2], [1, 4, 5, 0], [11, -6, -17, 12], [-3, 10, 7, 0], [-4, 6, 8, -6], [-2, 4, 0, 4], [3, -12, -9, 0], [8, 0, -5, 2], [13, -2, -15, 4], [4, -8, -15, 4], [-8, 6, 0, 6], [13, -2, -15, 4], [8, 0, -7, 6], [20, 0, -9, -2], [-7, 2, 9, -4], [-4, 8, -3, -4], [-10, 0, 5, 0], [3, -2, 1, 0], [-12, 12, 24, -12], [14, -4, 0, -4], [2, 8, -4, -8], [-1, 0, -1, 0], [-7, -4, 3, 8], [-4, 8, 15, -4], [0, 0, -9, 0], [15, 0, -15, 0], [10, 0, -5, 0], [11, 2, -9, -4], [0, -8, 0, 8], [-6, 12, 23, -6], [13, -2, 11, 0], [-14, 0, 28, 0], [2, 2, 0, 2], [-20, 6, 0, 6], [-2, -8, 4, 8], [5, -6, -1, 0], [14, 6, 0, 6], [7, -8, -15, 16], [-12, 0, 3, 6], [14, 0, -5, -4], [6, -20, -12, 20], [-6, 12, -3, -6], [13, 0, -13, 0], [-6, 0, -3, 12], [-1, -10, -11, 0], [8, -4, 0, -4], [11, -18, -7, 0], [-10, 0, 13, -16], [-5, 0, -5, 0], [4, -8, 9, 4], [0, -12, 0, 12], [22, 0, -7, -8], [1, 6, 5, -12], [-12, 24, 5, -12], [-8, 10, 0, 10], [-19, 10, -9, 0], [-2, 0, 1, 0], [3, 14, 17, 0], [18, -18, -36, 18], [-2, -8, 0, -8], [16, 0, -1, -14], [-9, 12, 3, 0], [-2, 4, -21, -2], [-2, -6, 4, 6], [7, 4, -3, -8], [22, 0, -7, -8], [-6, 12, 0, 12], [4, -8, 3, 4], [-6, 0, 12, 0], [12, 6, 0, 6], [-12, 0, 5, 2], [9, 0, -9, 0], [6, -12, -3, 6], [4, -14, 0, -14], [4, 0, -8, 0], [-12, 0, 17, -22], [-8, 16, 16, -16], [-18, 12, 0, 12], [10, -20, -9, 10], [3, 6, 3, -12], [-16, 0, 5, 6], [-3, -4, -7, 0], [14, -12, -28, 12], [-11, 6, -5, 0], [-11, 4, 15, -8], [5, 6, 11, 0], [0, 0, -27, 0], [-20, 40, 27, -20], [-9, 12, 21, -24], [12, 0, -9, 6], [-4, 8, 21, -4], [-14, 4, 0, 4], [-9, -8, -17, 0], [32, 0, -13, -6], [-10, -4, 0, -4], [-21, 0, -21, 0], [3, -12, -15, 24], [-32, 6, 0, 6], [10, -12, -20, 12], [38, 0, -13, -12], [28, 0, -7, -14], [6, -12, -7, 6], [6, -12, -5, 6], [-23, 2, -21, 0], [18, 0, -9, 0], [19, -4, 15, 0], [17, -6, 11, 0], [-19, 14, 33, -28], [-20, 40, 39, -20], [-26, 12, 52, -12], [24, 0, -11, -2], [35, 2, -33, -4], [-2, 16, 4, -16], [-8, 16, 27, -8], [-5, -16, -21, 0], [-8, -18, 16, 18], [12, -6, 0, -6], [6, -18, 0, -18], [10, 8, -20, -8], [3, -6, -3, 0], [12, -24, -27, 12], [-14, 18, 0, 18], [12, -24, -45, 12], [6, -12, 11, 6], [20, -10, 0, -10], [-47, 4, 51, -8], [5, -16, -11, 0], [-2, 12, 0, 12], [-10, 20, 20, -20], [14, 0, 3, -20], [-17, -14, 3, 28], [20, -6, -40, 6], [-3, -12, -9, 24], [-2, 0, -13, 28], [26, -22, -52, 22], [0, 0, 13, 0], [7, 4, -3, -8]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_325_n_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_325_2_n_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_325_2_n_c(:prec:=4)
    chi := MakeCharacter_325_n();
    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_325_2_n_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_325_2_n_c( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_325_n();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<2,R![1, 3, 2, -3, 1]>],Snew);
    return Vf;
end function;