
// Make newform 1334.2.a.a in Magma, downloaded from the LMFDB on 24 April 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_1334_a();"
// To make the coeffs of the qexp of the newform in the Hecke field type "qexpCoeffs();"
// To make the newform (type ModFrm), type "MakeNewformModFrm_1334_2_a_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_1334_2_a_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
        Kf := Rationals();
    end if;
    return [Kf!elt[1] : elt in input];
end function;


// To make the character of type GrpDrchElt, type "MakeCharacter_1334_a();"
function MakeCharacter_1334_a()
    N := 1334;
    order := 1;
    char_gens := [465, 553];
    v := [1, 1];
    // 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;

function MakeCharacter_1334_a_Hecke(Kf)
    return MakeCharacter_1334_a();
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], [4], [2], [6], [2], [-2], [1], [-1], [0], [4], [-2], [10], [8], [-8], [-4], [-8], [2], [-8], [6], [8], [-6], [6], [18], [-10], [0], [10], [4], [6], [16], [12], [10], [12], [0], [-8], [4], [-8], [-16], [-14], [-8], [20], [0], [-14], [26], [-20], [-4], [8], [-18], [-16], [-22], [-16], [-10], [-10], [6], [4], [26], [-8], [-22], [26], [-18], [-4], [-32], [-24], [22], [-6], [12], [-2], [0], [2], [-14], [-24], [-16], [32], [-10], [-16], [16], [22], [-26], [-38], [10], [20], [-20], [-22], [-8], [-24], [22], [14], [-6], [-16], [14], [4], [-16], [8], [-8], [-40], [-6], [30], [10], [34], [28], [-12], [-6], [-6], [18], [-2], [36], [-26], [40], [-10], [8], [36], [-42], [10], [-32], [42], [14], [-8], [46], [-18], [-20], [-50], [-36], [-4], [-20], [-20], [-40], [24], [8], [-12], [-32], [-4], [-52], [8], [34], [42], [0], [-26], [0], [-6], [36], [38], [32], [38], [2], [36], [-42], [10], [-24], [-48], [34], [-18], [12], [8], [26], [-48], [-12], [-18], [-22], [0], [-48], [6], [-40], [50], [22], [0], [-16], [10], [-18], [-26], [2], [34], [0], [-26], [16], [-6], [-40], [30], [12], [24], [48], [6], [-14], [42], [-60], [-12], [38], [-46], [-10], [-8], [-26], [36], [-38], [-58], [6], [-38], [-10], [-56], [18], [56], [0], [32], [58], [-58], [2], [-6], [16], [-12], [-18], [-40], [38], [38], [44], [-22], [48], [-34], [-8], [18], [-8], [22], [38], [-64], [18], [12], [16], [-18], [54], [-40], [-28], [-48], [-22], [22], [4], [6], [-50], [-24], [50], [-72], [-4], [0], [2], [-64], [56], [-34], [66], [24], [64], [58], [-26], [-60], [16], [42], [-12], [-42], [22], [0], [-24], [-18], [26], [-78], [52], [62], [10], [24], [18], [-78], [0], [70], [-14], [18], [-6], [-18], [26], [-68], [26], [80], [60], [-10], [-2], [22], [24], [-24], [76], [4], [-56], [-24], [-46], [40], [80], [-66], [56], [-78], [38], [82], [26], [-64], [-48], [-66], [16], [-4], [34], [-76], [80], [68], [62], [-78], [-72], [76], [-80], [-26], [8], [60], [-66], [-52], [-36], [26], [88], [48], [10], [30], [-86], [-18], [-58], [-16], [30], [10], [22], [68], [-68], [12], [-78], [94], [48], [-28], [2], [-64], [8], [46], [-54], [-8], [-26], [-74], [22], [-76], [84], [16], [-42], [88], [8], [-20], [56], [70], [-30], [4], [-64], [-14], [-60], [42], [82], [-80], [92], [-42], [-48], [-18], [4], [-26], [54], [44], [2], [96], [24], [24], [48], [88], [-50], [68], [0], [14], [-2], [42], [64], [-18], [-16], [30], [82], [-48], [-16], [50], [-26], [-8], [-74], [58], [28], [60], [-80], [54], [24], [-78], [86], [78], [-34], [78], [80], [6], [54], [64], [28], [78], [18], [-48], [-26], [30], [-62], [-62], [-18], [-6], [40], [8], [-46], [80], [44], [-100], [-8], [-60], [82], [6], [-98], [58], [-60], [-40]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_1334_a_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_1334_2_a_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_1334_2_a_a(:prec:=1)
    chi := MakeCharacter_1334_a();
    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_1334_2_a_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_1334_2_a_a( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_1334_a();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<3,R![0, 1]>,<5,R![0, 1]>],Snew);
    return Vf;
end function;