
// Make newform 77.2.m.a in Magma, downloaded from the LMFDB on 24 April 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_77_m();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_77_m_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_77_2_m_a();".
// 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_77_2_m_a();".
// 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, -1, 0, 1, -1, 1, 0, -1, 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_77_m();"
function MakeCharacter_77_m()
    N := 77;
    order := 15;
    char_gens := [45, 57];
    v := [10, 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_77_m_Hecke();"
function MakeCharacter_77_m_Hecke(Kf)
    N := 77;
    order := 15;
    char_gens := [45, 57];
    char_values := [[-1, 0, 0, 0, 0, -1, 0, 0], [-1, 0, 1, -1, 0, 0, -1, 1]];
    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, 0, 1, -1, 0, 1], [0, -1, 0, 0, 0, 0, -1, 0], [-1, 1, 0, 0, -1, -1, 0, -1], [-2, 0, 2, -2, -1, 0, -2, 2], [2, 0, -4, 2, -2, -1, 2, -2], [0, 0, 1, 3, 0, 0, 3, 1], [-2, 0, 0, -2, 2, 0, -2, 2], [-3, 6, 0, 0, 0, -3, 0, 3], [5, -2, 0, 0, -2, 5, 0, 0], [6, 0, -3, 6, 0, 0, 3, -3], [-1, 0, 6, -1, 1, -1, -1, 1], [0, -5, 0, 0, -3, 0, 0, -5], [-1, 0, 1, 0, 0, 0, -4, 1], [2, 0, 3, -3, 0, 0, 0, 3], [4, -6, 0, 0, 0, 4, 0, -4], [5, 0, -2, 5, -5, 5, 5, -5], [-6, 6, 0, -6, 6, 0, 0, 6], [2, -2, 0, 0, 6, 2, 0, 6], [1, -1, -1, 1, -1, 10, 0, -1], [-2, 0, 0, 2, 0, 0, -2, 0], [9, -3, -6, 9, -9, 0, 6, -9], [6, 0, 0, 0, -6, 6, 0, -9], [0, 0, 0, -9, 0, 0, 0, 0], [-8, 4, 0, 0, 4, -8, 0, 0], [0, 0, -1, 3, 0, 0, 3, -1], [-5, 0, -7, -5, 5, -5, -5, 5], [0, 0, 0, 0, 6, 0, 0, 0], [-10, 5, 0, 0, 0, -10, 0, 10], [-3, 3, 3, -3, 3, -5, 0, 3], [-5, 0, 5, 0, 0, 0, -6, 5], [-2, 0, 0, 1, 0, 0, -2, 0], [5, -7, 0, 0, -7, 5, 0, 0], [4, -11, 0, 4, -4, 11, -7, -4], [3, 0, -15, 3, 0, 0, 15, -15], [-7, 7, 0, 0, -10, -7, 0, -10], [0, 3, 1, 0, 0, 1, 3, 0], [0, 15, -2, 0, 0, -2, 15, 0], [-2, 0, 0, 0, 2, -2, 0, 18], [0, 0, 2, 8, 0, 0, 8, 2], [4, -17, 0, 0, 0, 4, 0, -4], [0, 7, -17, 0, 0, -17, 7, 0], [-10, 0, 0, -15, 0, 0, -10, 0], [0, 2, 0, 0, 13, 0, 0, 2], [12, -2, 0, 12, -12, 2, 10, -12], [3, 0, 1, -1, 0, 0, 0, 1], [-9, 9, 9, -9, 9, 7, 0, 9], [0, 0, 9, 0, 0, 0, 0, 9], [-3, 0, 3, 0, 0, 0, -24, 3], [0, -12, 12, 0, 0, 0, -12, 0], [-3, 0, 0, 0, 3, -3, 0, 4], [5, 0, 0, 0, -5, 5, 0, 0], [-6, 0, 6, 0, 0, 0, 3, 6], [-12, 12, 12, -12, 12, -21, 0, 12], [0, 0, -13, 7, 0, 0, 7, -13], [0, -8, 0, 0, -7, 0, 0, -8], [0, 0, 0, 0, 0, 12, 0, 0], [-8, -11, 0, -8, 8, 11, -19, 8], [0, 18, 0, 0, 4, 0, 0, 18], [6, 0, -9, 6, -6, 6, 6, -6], [14, 0, 0, -4, 0, 0, 14, 0], [0, 1, 12, 0, 0, 12, 1, 0], [10, 0, -6, 10, 0, 0, 6, -6], [3, 0, -17, 17, 0, 0, 0, -17], [0, -19, 20, 0, 0, 20, -19, 0], [-6, 6, 0, 0, -2, -6, 0, -2], [-1, 0, 0, 0, 1, -1, 0, -1], [11, -6, 0, 0, -6, 11, 0, 0], [-11, 0, 5, -11, 0, 0, -5, 5], [-30, 24, 0, -30, 30, -24, -6, 30], [-19, 0, 19, 0, 0, 0, -1, 19], [-4, 4, 4, -4, 4, -2, 0, 4], [0, -7, 0, 0, -5, 0, 0, -7], [18, -15, -3, 18, -18, 0, 3, -18], [-12, 22, 0, 0, 22, -12, 0, 0], [6, 0, 0, 18, 0, 0, 6, 0], [11, 0, 0, 0, -11, 11, 0, -16], [-26, -4, 30, -26, 26, 0, -30, 26], [9, -27, 0, 0, -27, 9, 0, 0], [-5, 5, 0, 0, 13, -5, 0, 13], [-10, 0, -9, -10, 10, -10, -10, 10], [17, 0, -10, 10, 0, 0, 0, -10], [6, 0, -6, 0, 0, 0, -18, -6], [-16, 0, 8, -16, 16, -16, -16, 16], [7, 0, 5, 7, 0, 0, -5, 5], [24, -10, 0, 0, -10, 24, 0, 0], [2, 11, 0, 0, 0, 2, 0, -2], [0, 0, -31, 2, 0, 0, 2, -31], [12, -12, 0, 0, -9, 12, 0, -9], [-11, 0, -5, 5, 0, 0, 0, -5], [-25, 0, 22, -22, 0, 0, 0, 22], [-9, 9, 0, 0, 5, -9, 0, 5], [15, -16, 0, 15, -15, 16, -1, -15], [0, 2, 4, 0, 0, 4, 2, 0], [-18, 0, 27, -18, 0, 0, -27, 27], [0, 12, 0, 0, -11, 0, 0, 12], [8, 0, -8, 0, 0, 0, -15, -8], [15, -24, 0, 0, 0, 15, 0, -15], [36, -13, -23, 36, -36, 0, 23, -36], [6, -6, 0, 0, 13, 6, 0, 13], [-22, 0, 0, 0, 22, -22, 0, 6], [31, 0, -31, 0, 0, 0, 15, -31], [7, -11, 4, 7, -7, 0, -4, -7], [-4, 0, 10, -4, 4, -4, -4, 4], [1, -13, 0, 0, 0, 1, 0, -1], [9, -9, -9, 9, -9, 7, 0, -9], [24, -15, 0, 24, -24, 15, 9, -24], [-31, 0, 17, -31, 0, 0, -17, 17], [-22, 26, 0, 0, 26, -22, 0, 0], [-19, 36, 0, -19, 19, -36, 17, 19], [21, 0, -24, 21, 0, 0, 24, -24], [15, 0, 0, 0, -15, 15, 0, 3], [0, -13, 4, 0, 0, 4, -13, 0], [19, 0, 4, -4, 0, 0, 0, 4], [0, -3, -27, 0, 0, -27, -3, 0], [5, 0, -12, 5, 0, 0, 12, -12], [0, 6, 15, 0, 0, 15, 6, 0], [0, 0, 0, -19, 0, 0, 0, 0], [2, 0, -10, 2, -2, 2, 2, -2], [0, 21, 0, 0, 33, 0, 0, 21], [-9, 0, 9, -9, 0, 0, 0, 9], [-9, 9, 9, -9, 9, -6, 0, 9], [0, 0, -27, 12, 0, 0, 12, -27], [-34, 34, 0, 0, 32, -34, 0, 32], [-10, 10, 10, -10, 10, 15, 0, 10], [24, 0, 0, 0, -24, 24, 0, -27], [-12, 0, 12, 0, 0, 0, 6, 12], [3, -3, 0, 0, -2, 3, 0, -2], [0, 10, 0, 0, -1, 0, 0, 10], [-9, 0, -12, 12, 0, 0, 0, -12], [0, -18, 0, 0, -22, 0, 0, -18], [-6, 0, 20, -6, 6, -6, -6, 6], [-4, 0, 0, -38, 0, 0, -4, 0], [-21, 27, 0, 0, 0, -21, 0, 21], [0, 0, -17, -1, 0, 0, -1, -17], [29, 0, 0, 0, -29, 29, 0, -17], [-10, 0, 4, -4, 0, 0, 0, 4], [0, 3, 12, 0, 0, 12, 3, 0], [31, -31, 0, 31, -31, 31, 0, -31], [-8, 0, 0, 2, 0, 0, -8, 0], [15, -18, 0, 15, -15, 18, -3, -15], [0, 0, 0, 0, 0, 0, 39, 0], [0, -17, 0, 0, -29, 0, 0, -17], [12, 0, -25, 12, -12, 12, 12, -12], [0, 0, 24, -7, 0, 0, -7, 24], [-12, -3, 15, -12, 12, 0, -15, 12], [41, 0, -41, 0, 0, 0, 28, -41], [32, 0, 0, 18, 0, 0, 32, 0], [4, -4, -4, 4, -4, -5, 0, -4], [-18, 6, 0, 0, 6, -18, 0, 0], [-14, 14, 0, 0, 34, -14, 0, 34], [17, -33, 0, 0, 0, 17, 0, -17], [-8, 0, -14, 14, 0, 0, 0, -14], [-28, 0, 28, 0, 0, 0, -13, 28], [0, -11, 0, 0, -6, 0, 0, -11], [39, -18, 0, 39, -39, 18, 21, -39], [0, 0, -2, 19, 0, 0, 19, -2], [-33, 33, 0, 0, 9, -33, 0, 9], [-41, 41, 0, 0, 9, -41, 0, 9], [0, 0, 4, -9, 0, 0, -9, 4], [5, 6, 0, 5, -5, -6, 11, -5], [-3, -16, 0, 0, -16, -3, 0, 0], [11, 0, -31, 11, 0, 0, 31, -31], [-5, 0, -21, 21, 0, 0, 0, -21], [0, -18, 0, 0, 0, 0, 0, 0], [-21, 0, 30, -21, 21, -21, -21, 21], [4, 25, -29, 4, -4, 0, 29, -4], [-13, 13, 13, -13, 13, -15, 0, 13], [36, -24, -12, 36, -36, 0, 12, -36]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_77_m_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_77_2_m_a();".
// 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_77_2_m_a(:prec:=8)
    chi := MakeCharacter_77_m();
    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_77_2_m_a();".
// 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_77_2_m_a( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_77_m();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<2,R![1, 3, 5, 8, 9, 2, 0, 2, 1]>],Snew);
    return Vf;
end function;