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Make ode functionality tested, add const-correctness #41311

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a2202a3
Make ode functionality tested, add const-correctness
user202729 Dec 19, 2025
bf6982f
Add some missing const qualifiers
user202729 Dec 19, 2025
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4 changes: 2 additions & 2 deletions src/sage/calculus/ode.pxd
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
cdef class ode_system:
cdef int c_j(self, double , double *, double *, double *) noexcept
cdef int c_j(self, double , const double *, double *, double *) noexcept

cdef int c_f(self, double t, double* , double*) noexcept
cdef int c_f(self, double t, const double* , double*) noexcept
55 changes: 26 additions & 29 deletions src/sage/calculus/ode.pyx
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Expand Up @@ -37,10 +37,10 @@
self.y_n = x

cdef class ode_system:
cdef int c_j(self, double t, double *y, double *dfdy, double *dfdt) noexcept:
cdef int c_j(self, double t, const double *y, double *dfdy, double *dfdt) noexcept:
return 0

cdef int c_f(self, double t, double* y, double* dydt) noexcept:
cdef int c_f(self, double t, const double* y, double* dydt) noexcept:
return 0

cdef int c_jac_compiled(double t, const double *y, double *dfdy, double *dfdt, void *params) noexcept:
Expand Down Expand Up @@ -303,35 +303,32 @@
is slow on systems that require many function evaluations. It
is possible to pass a compiled function by deriving from the
class :class:`ode_system` and overloading ``c_f`` and ``c_j`` with C
functions that specify the system. The following will work in the
notebook:

.. code-block:: cython

%cython
cimport sage.calculus.ode
import sage.calculus.ode
from sage.libs.gsl.all cimport *

cdef class van_der_pol(sage.calculus.ode.ode_system):
cdef int c_f(self, double t, double *y, double *dydt):
dydt[0]=y[1]
dydt[1]=-y[0]-1000*y[1]*(y[0]*y[0]-1)
return GSL_SUCCESS
cdef int c_j(self, double t, double *y, double *dfdy, double *dfdt):
dfdy[0]=0
dfdy[1]=1.0
dfdy[2]=-2.0*1000*y[0]*y[1]-1.0
dfdy[3]=-1000*(y[0]*y[0]-1.0)
dfdt[0]=0
dfdt[1]=0
return GSL_SUCCESS
functions that specify the system. (You can also use the ``%%cython``
cell magic, see :meth:`~sage.repl.ipython_extension.SageMagics.cython`.) ::

sage: cython('''

Check warning on line 309 in src/sage/calculus/ode.pyx

View workflow job for this annotation

GitHub Actions / Conda (ubuntu, Python 3.12, all, editable)

Warning: slow doctest: 

slow doctest:: Test ran for 5.28s cpu, 5.33s wall
Check ran for 0.00s cpu, 0.00s wall

Check warning on line 309 in src/sage/calculus/ode.pyx

View workflow job for this annotation

GitHub Actions / Conda (macos, Python 3.13, all)

Warning: slow doctest: 

slow doctest:: Test ran for 6.71s cpu, 10.96s wall
Check ran for 0.01s cpu, 0.00s wall
....: cimport sage.calculus.ode
....: import sage.calculus.ode
....: from sage.libs.gsl.all cimport *
....:
....: cdef class van_der_pol(sage.calculus.ode.ode_system):
....: cdef int c_f(self, double t, const double *y, double *dydt) noexcept:
....: dydt[0]=y[1]
....: dydt[1]=-y[0]-1000*y[1]*(y[0]*y[0]-1)
....: return GSL_SUCCESS
....: cdef int c_j(self, double t, const double *y, double *dfdy, double *dfdt) noexcept:
....: dfdy[0]=0
....: dfdy[1]=1.0
....: dfdy[2]=-2.0*1000*y[0]*y[1]-1.0
....: dfdy[3]=-1000*(y[0]*y[0]-1.0)
....: dfdt[0]=0
....: dfdt[1]=0
....: return GSL_SUCCESS
....: ''')

After executing the above block of code you can do the
following (WARNING: the following is *not* automatically
doctested)::
following::

sage: # not tested
sage: T = ode_solver()
sage: T.algorithm = "bsimp"
sage: vander = van_der_pol()
Expand Down Expand Up @@ -455,7 +452,7 @@
raise MemoryError("error allocating memory")
result = []
v = [0] * dim
cdef gsl_odeiv_step_type * T
cdef const gsl_odeiv_step_type * T

for i in range(dim): # copy initial conditions into C array
y[i] = self.y_0[i]
Expand Down
4 changes: 2 additions & 2 deletions src/sage/misc/cython.py
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Expand Up @@ -656,8 +656,8 @@ def compile_and_load(code, **kwds):
r"""
INPUT:

- ``code`` -- string containing code that could be in a .pyx file
that is attached or put in a %cython block in the notebook
- ``code`` -- string containing code that could be in a ``.pyx`` file
that is attached or put in a ``%%cython`` block

See the function :func:`sage.misc.cython.cython` for documentation
for the other inputs.
Expand Down
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