sage:from sage.modular.dirichlet import DirichletCharacter
H = DirichletGroup(1573, base_ring=CyclotomicField(2))
chi = DirichletCharacter(H, H._module([0, 0]))
N = Newforms(chi, 4, names="a")
magma://Please install CHIMP (https://github.com/edgarcosta/CHIMP) if you want to run this code
chi := DirichletCharacter("1573.1");
S:= CuspForms(chi, 4);
N := Newforms(S);
This newform subspace can be constructed as the kernel of the linear operator
\( T_{2}^{38} + 3 T_{2}^{37} - 238 T_{2}^{36} - 688 T_{2}^{35} + 25878 T_{2}^{34} + 71961 T_{2}^{33} + \cdots + 34\!\cdots\!64 \)
acting on \(S_{4}^{\mathrm{new}}(\Gamma_0(1573))\).