
// Make newform 7200.2.d.q in Magma, downloaded from the LMFDB on 25 April 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_7200_d();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_7200_d_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_7200_2_d_q();".
// 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_7200_2_d_q();".
// 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 := [8, -8, 6, -6, 3, -2, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rf_num := [[1, 0, 0, 0, 0, 0], [-2, 2, -1, 2, -1, 0], [8, -2, 4, -3, 0, -1], [-8, 10, -6, 3, -2, 1], [3, 0, 5, -1, 1, -1], [-12, 2, -6, 5, -2, 3]];
    Rf_basisdens := [1, 1, 2, 2, 1, 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_7200_d();"
function MakeCharacter_7200_d()
    N := 7200;
    order := 2;
    char_gens := [6751, 901, 6401, 577];
    v := [2, 1, 2, 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;

// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_7200_d_Hecke();"
function MakeCharacter_7200_d_Hecke(Kf)
    N := 7200;
    order := 2;
    char_gens := [6751, 901, 6401, 577];
    char_values := [[1, 0, 0, 0, 0, 0], [-1, 0, 0, 0, 0, 0], [1, 0, 0, 0, 0, 0], [-1, 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, 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, 1, -1, 0, -1], [0, -1, 0, 0, 0, 0], [0, 0, -1, -1, 0, 0], [0, 0, -1, 0, 0, 1], [0, 0, 1, 0, 0, -1], [0, 0, 1, 0, 0, 0], [2, 1, 0, 0, 0, 0], [-1, 0, 0, 0, 1, 0], [3, 1, 0, 0, -1, 0], [-1, -1, 0, 0, 1, 0], [0, 0, 1, -2, 0, -1], [2, 0, 0, 0, 0, 0], [0, 0, -1, -1, 0, -1], [0, 0, 2, -2, 0, -2], [4, 0, 0, 0, 0, 0], [-1, 1, 0, 0, 1, 0], [0, 0, 3, 0, 0, 0], [6, -1, 0, 0, 0, 0], [-5, -1, 0, 0, 1, 0], [-5, 1, 0, 0, -1, 0], [0, 0, 3, 2, 0, 0], [0, 0, 1, 0, 0, 0], [0, 0, 0, 2, 0, -1], [-7, 3, 0, 0, -1, 0], [0, 0, 0, 0, 0, 2], [0, 0, 3, 1, 0, 4], [0, 0, 4, 2, 0, -1], [0, 0, -1, 1, 0, 3], [0, 0, 5, -1, 0, 0], [0, 0, -5, -2, 0, 1], [0, 0, 1, 0, 0, 0], [-5, 2, 0, 0, -1, 0], [9, 2, 0, 0, -1, 0], [-7, 1, 0, 0, -1, 0], [0, 0, 3, -2, 0, -1], [4, 0, 0, 0, -2, 0], [0, 0, 3, 1, 0, -1], [0, 0, -8, 0, 0, 2], [-8, 0, 0, 0, 0, 0], [0, 0, -5, 2, 0, 4], [14, 2, 0, 0, 0, 0], [-13, 2, 0, 0, -1, 0], [0, 0, -5, -2, 0, -3], [0, 0, -6, -2, 0, -1], [0, -2, 0, 0, 0, 0], [0, 0, -4, -2, 0, 2], [0, 0, -7, 1, 0, 0], [-11, 1, 0, 0, -1, 0], [4, 0, 0, 0, -2, 0], [0, 0, 1, -3, 0, 3], [0, 0, -3, 3, 0, 0], [0, 0, 7, -2, 0, -1], [0, 0, -3, 0, 0, -4], [-21, -2, 0, 0, -1, 0], [-3, 4, 0, 0, -1, 0], [4, 0, 0, 0, -2, 0], [20, 0, 0, 0, 0, 0], [2, 4, 0, 0, 0, 0], [15, 3, 0, 0, 1, 0], [7, -1, 0, 0, -3, 0], [0, 0, -3, 2, 0, 0], [-10, -2, 0, 0, 4, 0], [0, 0, 7, -4, 0, -3], [0, 0, 3, -4, 0, -4], [6, 0, 0, 0, 2, 0], [0, 0, 6, -2, 0, -6], [0, 0, -1, -1, 0, 4], [1, -1, 0, 0, -1, 0], [0, 0, 2, -4, 0, -5], [-9, 0, 0, 0, 1, 0], [0, 0, -1, 2, 0, -3], [0, 0, -1, 0, 0, -1], [0, 0, 5, -4, 0, 0], [2, -1, 0, 0, 2, 0], [5, 1, 0, 0, 1, 0], [6, 4, 0, 0, 0, 0], [0, 0, 1, -3, 0, -1], [0, 0, -12, -2, 0, 2], [-1, 1, 0, 0, 1, 0], [0, 0, 1, -4, 0, 0], [1, 0, 0, 0, 1, 0], [6, -4, 0, 0, 2, 0], [-18, -4, 0, 0, 0, 0], [0, 0, 5, -2, 0, 4], [0, 0, -7, 0, 0, 4], [0, 0, 10, 0, 0, -1], [19, 3, 0, 0, 1, 0], [15, -3, 0, 0, 1, 0], [0, 0, 4, 2, 0, 3], [0, 0, 7, -1, 0, -1], [0, 0, 3, 4, 0, 1], [0, 0, 5, 2, 0, 3], [0, 0, -7, -4, 0, 8], [-10, 0, 0, 0, 0, 0], [0, 0, 0, 0, -4, 0], [0, 0, 4, -4, 0, 2], [-5, -1, 0, 0, -3, 0], [-16, 0, 0, 0, -2, 0], [10, 4, 0, 0, -2, 0], [15, -1, 0, 0, -1, 0], [0, 0, 7, 0, 0, 1], [0, 0, 3, -2, 0, -4], [-9, -3, 0, 0, 1, 0], [0, 0, -1, 1, 0, 0], [-15, -5, 0, 0, -1, 0], [-2, 0, 0, 0, 4, 0], [0, 0, 8, -4, 0, -1], [-4, 1, 0, 0, 0, 0], [0, 0, -9, 3, 0, 0], [0, 0, -9, -2, 0, 1], [16, 1, 0, 0, -2, 0], [8, 4, 0, 0, 2, 0], [-1, -5, 0, 0, 1, 0], [0, 0, -3, 6, 0, 11], [6, -2, 0, 0, 4, 0], [0, 0, 3, 3, 0, 7], [0, 0, -6, -2, 0, -6], [0, 0, 9, 0, 0, 0], [6, -2, 0, 0, -4, 0], [27, -1, 0, 0, 1, 0], [0, 0, -5, 0, 0, 5], [0, 0, -9, 4, 0, 4], [0, 0, -8, -2, 0, -2], [-14, 0, 0, 0, 2, 0], [0, 0, 0, -6, 0, -9], [-9, -2, 0, 0, 5, 0], [0, 0, 11, -8, 0, -7], [0, 0, 11, 4, 0, -1], [-14, 5, 0, 0, 0, 0], [-21, -2, 0, 0, 1, 0], [-4, 6, 0, 0, 2, 0], [-2, -6, 0, 0, 0, 0], [2, 2, 0, 0, 0, 0], [10, 6, 0, 0, 2, 0], [-10, 0, 0, 0, 0, 0], [16, -8, 0, 0, 2, 0], [0, 0, -5, 6, 0, -3], [0, 0, 13, 4, 0, -4], [0, 0, -2, 6, 0, 3], [-20, 0, 0, 0, 0, 0], [0, 0, 16, 0, 0, 2], [11, -3, 0, 0, 5, 0], [8, -3, 0, 0, -4, 0], [0, 0, -3, -3, 0, -4], [0, 0, 3, -2, 0, 5], [0, 0, -5, 6, 0, 7], [-3, -2, 0, 0, 3, 0], [3, -7, 0, 0, -1, 0], [-7, 9, 0, 0, -1, 0], [0, 0, -5, -6, 0, -5], [-14, -6, 0, 0, 2, 0], [5, -7, 0, 0, -1, 0], [28, -1, 0, 0, -2, 0], [-12, 2, 0, 0, 2, 0], [0, 0, 7, 0, 0, -12], [0, 0, -7, 0, 0, -4], [-4, 4, 0, 0, 0, 0], [0, 0, 11, -3, 0, 4], [0, 0, 6, -2, 0, 7], [0, 0, 9, 5, 0, -5], [0, 0, 3, -1, 0, 4], [0, 0, -1, 0, 0, 11], [11, -4, 0, 0, 3, 0], [-4, -7, 0, 0, 0, 0], [22, -2, 0, 0, 4, 0], [-14, 4, 0, 0, -4, 0], [0, 0, -5, 7, 0, -1], [0, 0, -6, 12, 0, 6], [12, -12, 0, 0, 4, 0], [0, 0, 5, 2, 0, 4], [28, -3, 0, 0, 2, 0], [-19, 3, 0, 0, -3, 0], [0, 0, 3, 2, 0, -7], [0, 0, 19, 0, 0, -4], [0, 0, 4, 0, 0, 3], [0, 0, -18, 4, 0, 2], [0, 0, -6, 2, 0, -5], [0, 0, 1, 3, 0, 7], [12, -1, 0, 0, -4, 0], [0, 0, 3, -7, 0, 0], [0, 0, -21, 0, 0, -5], [0, 0, 13, 4, 0, -4], [41, -4, 0, 0, 3, 0], [3, -1, 0, 0, -3, 0], [0, -10, 0, 0, 2, 0], [-6, 2, 0, 0, -2, 0], [0, 0, 3, -6, 0, -8], [18, 2, 0, 0, -6, 0], [0, 0, -5, -2, 0, -7], [0, 0, -19, 0, 0, 0], [5, 3, 0, 0, -5, 0], [0, 0, 1, -5, 0, -4], [18, -4, 0, 0, 4, 0], [-22, 9, 0, 0, -2, 0], [0, 0, -15, 3, 0, 8], [0, 0, 23, -4, 0, -1], [0, 0, 7, -8, 0, -12], [-16, -3, 0, 0, 6, 0], [2, -3, 0, 0, -2, 0], [-8, 4, 0, 0, -6, 0], [0, 0, 13, 1, 0, -5], [-18, -8, 0, 0, -4, 0], [-2, -7, 0, 0, -4, 0], [2, 4, 0, 0, 6, 0], [5, 3, 0, 0, 5, 0], [0, 0, -1, 0, 0, 9], [0, 0, 5, -6, 0, 4], [0, 0, -5, -4, 0, 8], [0, 0, 28, 2, 0, -1], [22, 2, 0, 0, -2, 0], [-18, 8, 0, 0, -2, 0], [4, -8, 0, 0, 6, 0], [0, 0, -2, 4, 0, 3], [3, -5, 0, 0, 3, 0], [0, 0, 7, 0, 0, -9], [-18, 12, 0, 0, -4, 0], [0, 0, 0, 2, 0, -10], [-21, 2, 0, 0, -1, 0], [-5, 9, 0, 0, -1, 0], [0, 0, 2, -8, 0, -9], [-15, -7, 0, 0, 3, 0], [0, 0, -10, 4, 0, 10], [0, 0, -7, -1, 0, 16], [32, -2, 0, 0, 4, 0], [0, 0, 6, 0, 0, -1], [0, 0, 3, 5, 0, 7], [46, -3, 0, 0, 2, 0], [0, 0, -9, -2, 0, -7], [-13, -6, 0, 0, -1, 0], [-2, -2, 0, 0, -4, 0], [-50, -6, 0, 0, -2, 0], [0, 0, -3, 4, 0, 7], [16, 8, 0, 0, 2, 0], [-14, -6, 0, 0, 4, 0], [0, 0, -7, -3, 0, 11], [19, -11, 0, 0, 5, 0], [12, -6, 0, 0, 4, 0], [0, 0, 11, 8, 0, 9], [0, 0, 14, -10, 0, -1], [0, 0, -2, -2, 0, -10], [0, 0, 19, -1, 0, -8], [-44, -6, 0, 0, 0, 0], [0, 0, -2, -4, 0, 3], [0, 0, 19, -1, 0, -1], [0, 0, -13, -4, 0, -3], [0, 0, -9, -6, 0, -5], [28, -13, 0, 0, 4, 0], [6, 4, 0, 0, 0, 0], [0, 0, 1, -8, 0, 3], [20, 4, 0, 0, 6, 0], [4, 0, 0, 0, 2, 0], [0, 0, 23, 3, 0, -1], [0, 0, -12, 0, 0, -10], [7, -5, 0, 0, 1, 0], [24, -4, 0, 0, 6, 0], [0, 0, -15, -4, 0, -12], [0, 0, 6, -10, 0, -17], [-8, -4, 0, 0, 4, 0], [0, 0, -16, -2, 0, 2], [-49, -4, 0, 0, 1, 0], [0, 0, -21, -3, 0, -4], [0, 0, 15, 4, 0, 1], [0, 0, -9, -4, 0, 4], [43, -1, 0, 0, 3, 0], [2, 6, 0, 0, 2, 0], [30, 4, 0, 0, 0, 0], [0, 0, -2, -8, 0, -2], [-27, -3, 0, 0, -5, 0], [0, 0, 5, 2, 0, 4], [18, 3, 0, 0, -4, 0], [0, 0, 13, 2, 0, 8], [0, 0, 4, 6, 0, -9], [16, 2, 0, 0, 0, 0], [0, 0, 6, 2, 0, 2], [4, 8, 0, 0, -2, 0], [0, 0, 15, 5, 0, -9], [0, 0, -3, -4, 0, -5], [17, 6, 0, 0, 5, 0], [0, 0, -11, 6, 0, -1], [0, 0, 18, 0, 0, -6], [36, -8, 0, 0, 0, 0], [-22, -2, 0, 0, 6, 0], [0, 0, -5, 8, 0, -4], [26, -2, 0, 0, 0, 0], [5, 2, 0, 0, 1, 0], [23, 3, 0, 0, -1, 0], [0, 0, 17, 4, 0, -8], [-5, -7, 0, 0, 5, 0], [0, 0, -3, 13, 0, 0], [0, 0, -9, -11, 0, -1], [17, 6, 0, 0, -9, 0], [0, 0, -5, -12, 0, 0], [-8, -3, 0, 0, -2, 0], [40, 0, 0, 0, -6, 0], [0, 0, -31, -3, 0, -1], [-49, 3, 0, 0, 1, 0], [0, 0, 5, 10, 0, 8], [-10, -12, 0, 0, 0, 0], [19, -2, 0, 0, -1, 0], [41, 3, 0, 0, -1, 0], [0, 0, -1, -4, 0, -15], [0, 0, -11, -4, 0, 12], [17, 9, 0, 0, 3, 0], [0, 0, -12, -2, 0, -10], [22, 4, 0, 0, -10, 0], [43, 4, 0, 0, -3, 0], [0, 0, -25, 6, 0, 3], [0, 0, -9, 0, 0, 0], [-11, -7, 0, 0, -7, 0], [6, -6, 0, 0, -2, 0], [0, 0, 19, -4, 0, -5], [46, -2, 0, 0, 4, 0], [0, 0, -9, 13, 0, 7], [-20, 14, 0, 0, -8, 0], [0, 0, -19, 0, 0, 4], [3, 7, 0, 0, -5, 0], [0, 0, 3, 0, 0, -11], [0, 0, 3, -10, 0, -8], [0, 0, -5, -8, 0, -12], [0, 0, -4, 2, 0, 15], [0, 0, -9, 7, 0, 16], [-6, 8, 0, 0, 4, 0], [0, 0, -13, -6, 0, 9], [9, 5, 0, 0, -1, 0], [0, 0, -21, 4, 0, -1], [10, 4, 0, 0, 4, 0], [0, 0, 16, 6, 0, 2], [24, -4, 0, 0, -2, 0], [40, 7, 0, 0, 2, 0], [21, 3, 0, 0, -5, 0], [0, 0, -5, -6, 0, -19], [3, -9, 0, 0, 1, 0], [0, 0, 6, 4, 0, 18], [0, 0, 11, 7, 0, -12], [-6, 0, 0, 0, 0, 0], [0, 0, 24, -2, 0, 3], [11, -4, 0, 0, 5, 0], [0, 0, -7, 9, 0, 12], [0, 0, -9, -4, 0, 12], [-5, -8, 0, 0, 3, 0], [0, -8, 0, 0, -2, 0], [0, 0, 1, 3, 0, 19], [0, 0, -8, 14, 0, 18], [-8, 4, 0, 0, -4, 0], [-56, -2, 0, 0, -4, 0], [-38, 4, 0, 0, 4, 0], [0, 0, 3, 10, 0, 13], [0, 0, -11, -10, 0, -4], [0, 0, 7, -12, 0, -4], [0, 0, -26, 10, 0, 7], [0, 0, 26, -6, 0, -6], [0, 0, -11, 5, 0, 0], [-42, -6, 0, 0, 2, 0], [0, 0, 15, 5, 0, 19], [0, 0, 31, 1, 0, 8], [0, 0, 31, 2, 0, -5], [-14, 11, 0, 0, -6, 0], [-3, 9, 0, 0, 1, 0], [0, 0, -5, -8, 0, -5], [0, 0, -31, 1, 0, -1], [-20, 4, 0, 0, 0, 0], [0, 0, 3, -14, 0, 0], [18, 0, 0, 0, 8, 0], [0, 0, -6, 16, 0, 15], [24, 6, 0, 0, -6, 0], [0, 0, 9, 5, 0, 11], [0, 0, -29, 2, 0, 9], [0, 0, 15, 4, 0, -5], [0, 0, -5, -4, 0, -20], [55, -2, 0, 0, -5, 0], [-46, 1, 0, 0, -2, 0], [0, 0, -11, -9, 0, -9], [-51, -3, 0, 0, -1, 0], [0, 0, -9, 12, 0, 8], [40, 2, 0, 0, 6, 0], [0, 0, -21, 4, 0, 8], [0, 0, 13, 4, 0, -12], [0, 0, 27, -7, 0, -4], [0, 0, 0, -8, 0, -1], [0, 0, -15, -3, 0, 0], [0, 0, -1, 10, 0, -7], [0, 0, 7, -10, 0, -5], [34, -3, 0, 0, 0, 0], [21, -8, 0, 0, 7, 0], [9, 1, 0, 0, -9, 0], [0, 0, 9, 12, 0, -9], [14, 6, 0, 0, -8, 0], [-32, -12, 0, 0, -2, 0], [0, 0, -1, 3, 0, 19], [-16, -4, 0, 0, 4, 0], [52, -4, 0, 0, -4, 0], [0, 0, 11, -6, 0, -12], [-17, -4, 0, 0, 7, 0], [8, 8, 0, 0, 2, 0], [0, 0, -29, -4, 0, 1], [0, 0, -9, 0, 0, -16], [0, 0, 2, 4, 0, 2], [0, 0, -23, -5, 0, -8], [0, 0, 24, 2, 0, 3], [0, 0, -19, -9, 0, -8], [0, 0, 7, 12, 0, 4], [-22, -5, 0, 0, -4, 0], [-28, -9, 0, 0, -4, 0], [7, -5, 0, 0, 7, 0], [-13, -5, 0, 0, 5, 0], [0, 0, -19, 9, 0, 3], [0, 0, 29, -6, 0, -4], [-46, 4, 0, 0, 0, 0], [-29, -13, 0, 0, -7, 0], [0, 0, 11, -16, 0, -3], [0, 0, 21, 12, 0, -8], [0, 0, 19, 0, 0, 8], [-32, 16, 0, 0, -8, 0], [0, 0, 12, 8, 0, -1], [0, 0, 11, 9, 0, -8], [0, 0, 25, 4, 0, 7], [0, 0, 7, 12, 0, 8], [-8, 5, 0, 0, -4, 0], [0, 0, -25, -4, 0, -9], [0, 0, 5, -13, 0, -21], [0, 0, 21, -6, 0, -8], [34, -12, 0, 0, 8, 0], [41, -15, 0, 0, 3, 0], [-12, 14, 0, 0, -6, 0], [0, 0, -9, -4, 0, 9], [73, 3, 0, 0, -1, 0]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_7200_d_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_7200_2_d_q();".
// 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_7200_2_d_q(:prec:=6)
    chi := MakeCharacter_7200_d();
    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_7200_2_d_q();".
// 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_7200_2_d_q( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_7200_d();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,2,sign)));
    Vf := Kernel([<7,R![256, 0, 320, 0, 36, 0, 1]>,<11,R![4096, 0, 1088, 0, 64, 0, 1]>,<13,R![-16, -28, 0, 1]>,<37,R![-256, -60, 4, 1]>,<41,R![232, -36, -10, 1]>,<53,R![-2, 1]>],Snew);
    return Vf;
end function;