
// Make newform 4608.2.k.d in Magma, downloaded from the LMFDB on 24 April 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_4608_k();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_4608_k_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_4608_2_k_d();".
// 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_4608_2_k_d();".
// 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 := [1, 0, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rfbasis := [Kf.1^i : i in [0..Degree(Kf)-1]];
    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_4608_k();"
function MakeCharacter_4608_k()
    N := 4608;
    order := 4;
    char_gens := [3583, 2053, 4097];
    v := [4, 3, 4];
    // 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_4608_k_Hecke();"
function MakeCharacter_4608_k_Hecke(Kf)
    N := 4608;
    order := 4;
    char_gens := [3583, 2053, 4097];
    char_values := [[1, 0], [0, 1], [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 := [[0, 0], [0, 0], [-1, -1], [0, -4], [-4, -4], [-3, 3], [6, 0], [-4, 4], [0, 8], [-3, 3], [-4, 0], [-1, -1], [0, 2], [-4, -4], [-8, 0], [7, 7], [0, 0], [3, -3], [8, -8], [0, 0], [0, -10], [12, 0], [4, -4], [0, 16], [8, 0], [7, 7], [0, 4], [8, 8], [-5, 5], [16, 0], [-4, 0], [8, -8], [0, -2], [0, 0], [-1, -1], [0, -4], [3, -3], [-12, 12], [0, -8], [-11, 11], [-8, 8], [-9, -9], [-24, 0], [8, 0], [1, 1], [0, -4], [-16, 16], [12, 0], [12, -12], [7, 7], [0, 16], [-8, 0], [-24, 0], [-4, -4], [0, 0], [0, 16], [-3, 3], [-28, 0], [-15, -15], [0, 0], [8, 8], [1, 1], [24, -24], [0, 16], [0, 8], [-19, 19], [16, 16], [-30, 0], [-20, -20], [-11, 11], [16, 0], [0, 16], [20, 0], [15, 15], [-12, -12], [24, 0], [25, 25], [-27, 27], [-6, 0], [0, 8], [-12, 12], [-9, -9], [-8, 0], [8, 0], [0, 20], [12, 12], [10, 0], [0, -8], [19, -19], [4, 0], [4, -4], [-16, 0], [0, -12], [8, 8], [-8, 8], [0, 16], [11, -11], [0, -30], [-12, -12], [-3, 3], [-12, 12], [-11, 11], [-20, 20], [0, -18], [24, 24], [-18, 0], [16, 16], [-16, 0], [0, -40], [0, 38], [12, 0], [-7, -7], [0, 32], [0, 0], [0, -20], [-22, 0], [12, -12], [0, -24], [19, -19], [8, -8], [-7, -7], [-8, 0], [9, 9], [12, 12], [-36, 36], [11, -11], [33, 33], [0, 0], [0, 52], [-37, 37], [24, -24], [0, 24], [-28, 0], [7, 7], [0, 18], [40, 0], [-9, -9], [12, -12], [5, -5], [0, -2], [4, 4], [39, 39], [0, 44], [-32, -32], [29, -29], [0, 48], [-1, -1], [0, -18], [-12, -12], [-24, 0], [5, -5], [0, 0], [4, -4], [0, 48], [28, 28], [-40, 0], [0, -20], [-42, 0], [0, 26], [35, -35], [-40, 40], [0, -18], [0, -20], [-28, -28], [-38, 0], [0, 32], [44, 0], [-33, -33], [-40, 0], [-33, -33], [-8, -8], [37, -37], [0, 8], [0, -6], [-28, 0], [0, 32], [-8, -8], [25, 25], [0, 28], [3, -3], [4, 0], [-20, 20], [-25, -25], [0, 0], [24, 0], [-17, -17], [-19, 19], [-24, 24], [0, 40], [-32, 0], [-30, 0], [-16, -16], [-8, 8], [35, -35], [24, -24], [0, 0], [2, 0], [13, -13], [0, 0], [0, -48], [-43, 43], [-20, 0], [-15, -15], [14, 0], [-20, -20], [45, -45], [-20, 0], [-28, 28], [0, -16], [-12, -12], [56, 0], [-17, -17], [0, -44], [32, 32], [0, 0], [0, -56], [-12, 0], [-26, 0], [0, 8], [-45, 45], [-41, -41], [0, -4], [-42, 0], [-52, 0], [20, -20], [15, 15], [0, -48], [-16, 0], [0, -36], [24, 24], [11, -11], [12, -12], [60, 0], [0, 0], [20, 20], [0, 0], [24, 0], [15, 15], [20, 20], [0, -24], [-36, 36], [40, 40], [0, 44], [51, -51], [0, 0], [0, 48], [-52, 0], [8, -8], [40, 40], [-48, 0], [27, -27], [48, 0], [0, 40], [0, -26], [29, -29], [16, -16], [-9, -9], [0, 0], [-25, -25], [0, -40], [4, 0], [16, -16], [-31, -31], [-27, 27], [-42, 0], [24, -24], [-13, 13], [0, -80], [12, 12], [-39, -39], [51, -51], [0, 0], [0, 22], [-44, 0], [-14, 0], [0, -20], [-44, -44], [3, -3], [0, 74], [-48, 48], [-48, 0], [0, -20], [0, -8], [25, 25], [20, 20], [80, 0], [40, 0], [-23, -23], [0, -12], [48, 0], [-45, 45], [-40, 40], [0, 48], [-56, -56], [5, -5], [-27, 27], [68, 0], [1, 1], [-4, -4], [4, -4], [0, 24], [5, -5], [-44, 0], [-16, 16], [4, 4], [-8, 0], [-12, -12], [29, -29], [0, 0], [15, 15], [-72, 0], [17, 17], [10, 0], [-36, 36], [0, 0], [0, 6], [16, -16], [-48, 0], [-18, 0], [-16, 0], [-24, 24], [0, 8], [-19, 19], [-20, 0], [0, -30], [-8, 0], [-20, 20], [36, 36], [48, 0], [31, 31], [61, -61], [-45, 45], [44, 0], [56, -56], [-48, -48], [44, 44], [-11, 11], [16, 0], [0, -22], [-68, 0], [-7, -7], [0, 78], [7, 7], [0, 12], [-5, 5], [-60, 60], [-25, -25], [-8, -8], [-16, 0], [-15, -15], [36, -36], [0, 56], [-37, 37], [4, 0], [41, 41], [0, 32], [56, 0], [32, 32], [38, 0], [0, -32], [15, 15], [0, -48], [24, 0], [-52, -52], [-16, 16], [0, -42], [-21, 21], [0, 92], [0, 56], [-28, 28], [60, 60], [16, 0], [23, 23], [0, 20], [27, -27], [28, -28], [88, 0], [-62, 0], [58, 0], [0, -72], [67, -67], [0, 94], [0, -36], [96, 0], [-36, 36], [0, 56], [-44, 0], [-15, -15], [-16, -16], [72, 0], [98, 0], [-39, -39], [24, 24], [44, -44], [0, -72], [0, -24], [84, 0], [0, 34], [4, 4], [41, 41], [-27, 27], [-10, 0], [-36, 0], [0, 78], [-31, -31], [0, 20], [-35, 35], [90, 0], [60, -60], [-28, 28], [-34, 0], [-7, -7], [-4, -4], [-36, 36], [0, -22], [11, -11], [-8, 0], [0, 12], [-38, 0], [0, 32], [-11, 11], [-1, -1], [96, 0], [-28, -28], [0, -8], [-5, 5], [44, -44], [0, 80], [-36, -36], [0, 72]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_4608_k_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_4608_2_k_d();".
// 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_4608_2_k_d(:prec:=2)
    chi := MakeCharacter_4608_k();
    f_vec := qexpCoeffs();
    Kf := Universe(f_vec);
    // SetVerbose("ModularForms", true);
    // SetVerbose("ModularSymbols", true);
    S := CuspidalSubspace(ModularForms(chi, 2));
    S := BaseChange(S, Kf);
    maxprec := NextPrime(2999) - 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_4608_2_k_d();".
// 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_4608_2_k_d( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_4608_k();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<5,R![2, 2, 1]>,<7,R![16, 0, 1]>,<11,R![32, 8, 1]>,<13,R![18, 6, 1]>,<19,R![32, 8, 1]>],Snew);
    return Vf;
end function;