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Use fmpz_mod_mat in FLINT >= 3.1.0 #393

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Merged
oscarbenjamin merged 1 commit into from
May 22, 2026
Merged

Use fmpz_mod_mat in FLINT >= 3.1.0 #393

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22 changes: 22 additions & 0 deletions src/flint/flintlib/types/fmpz_mod_mat_compat.pxd
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,9 @@ from flint.flintlib.types.fmpz_mod cimport fmpz_mod_ctx_t, fmpz_mod_mat_t, fmpz_

cdef extern from *:
"""
#include <flint/fmpz_mod.h>
#include <flint/fmpz_mod_poly.h>

/*
* fmpz_mod_mat function signatures were changed in FLINT 3.1.0
*/
Expand All @@ -28,6 +31,7 @@ cdef extern from *:
#define compat_fmpz_mod_mat_transpose(B, A, ctx) fmpz_mod_mat_transpose(B, A, ctx)
#define compat_fmpz_mod_mat_solve(X, A, B, ctx) fmpz_mod_mat_solve(X, A, B, ctx)
#define compat_fmpz_mod_mat_rref(mat, ctx) fmpz_mod_mat_rref(mat, mat, ctx)
#define compat_fmpz_mod_mat_det(res, mat, ctx) fmpz_mod_mat_det(res, mat, ctx)
#define compat_fmpz_mod_mat_charpoly(p, M, ctx) fmpz_mod_mat_charpoly(p, M, ctx)
#define compat_fmpz_mod_mat_minpoly(p, M, ctx) fmpz_mod_mat_minpoly(p, M, ctx)

Expand All @@ -53,9 +57,26 @@ cdef extern from *:
#define compat_fmpz_mod_mat_transpose(B, A, ctx) fmpz_mod_mat_transpose(B, A)
#define compat_fmpz_mod_mat_solve(X, A, B, ctx) fmpz_mod_mat_solve(X, A, B)
#define compat_fmpz_mod_mat_rref(mat, ctx) fmpz_mod_mat_rref(NULL, mat)
#define compat_fmpz_mod_mat_det(res, mat, ctx) compat_fmpz_mod_mat_det_fallback(res, mat, ctx)
#define compat_fmpz_mod_mat_charpoly(p, M, ctx) fmpz_mod_mat_charpoly(p, M, ctx)
#define compat_fmpz_mod_mat_minpoly(p, M, ctx) fmpz_mod_mat_minpoly(p, M, ctx)

/* fmpz_mod_mat_det was added in FLINT 3.1.0 */
static inline void
compat_fmpz_mod_mat_det_fallback(fmpz_t res, const fmpz_mod_mat_t mat, const fmpz_mod_ctx_t ctx)
{
fmpz_mod_poly_t p;

fmpz_mod_poly_init(p, ctx);
fmpz_mod_mat_charpoly(p, mat, ctx);
fmpz_mod_poly_get_coeff_fmpz(res, p, 0, ctx);

if (fmpz_mod_mat_nrows(mat) % 2)
fmpz_mod_neg(res, res, ctx);

fmpz_mod_poly_clear(p, ctx);
}

#endif
"""

Expand All @@ -81,6 +102,7 @@ cdef extern from "flint/fmpz_mod_mat.h":
void compat_fmpz_mod_mat_transpose(fmpz_mod_mat_t B, const fmpz_mod_mat_t A, const fmpz_mod_ctx_t ctx)
int compat_fmpz_mod_mat_solve(fmpz_mod_mat_t X, const fmpz_mod_mat_t A, const fmpz_mod_mat_t B, const fmpz_mod_ctx_t ctx)
slong compat_fmpz_mod_mat_rref(fmpz_mod_mat_t mat, const fmpz_mod_ctx_t ctx)
void compat_fmpz_mod_mat_det(fmpz_t res, const fmpz_mod_mat_t mat, const fmpz_mod_ctx_t ctx)
void compat_fmpz_mod_mat_charpoly(fmpz_mod_poly_t p, const fmpz_mod_mat_t M, const fmpz_mod_ctx_t ctx)
void compat_fmpz_mod_mat_minpoly(fmpz_mod_poly_t p, const fmpz_mod_mat_t M, const fmpz_mod_ctx_t ctx)
#
Expand Down
14 changes: 8 additions & 6 deletions src/flint/types/fmpz_mod_mat.pyx
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ from flint.flintlib.types.fmpz_mod_mat_compat cimport (
compat_fmpz_mod_mat_transpose,
compat_fmpz_mod_mat_solve,
compat_fmpz_mod_mat_rref,
compat_fmpz_mod_mat_det,
compat_fmpz_mod_mat_charpoly,
compat_fmpz_mod_mat_minpoly,
)
Expand Down Expand Up @@ -501,12 +502,13 @@ cdef class fmpz_mod_mat(flint_mat):
fmpz_mod(5, 7)

"""
# XXX: No fmpz_mod_mat_det function...
p = self.charpoly()
p0 = p[0]
if self.nrows() % 2:
p0 = -p0
return p0
cdef fmpz_mod d
if self.nrows() != self.ncols():
raise ValueError("fmpz_mod_mat det: matrix must be square")
d = fmpz_mod.__new__(fmpz_mod)
d.ctx = self.ctx
compat_fmpz_mod_mat_det(d.val, self.val, self.ctx.val)
return d

def charpoly(self):
"""Return the characteristic polynomial of a matrix.
Expand Down