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# Array API Standard Support: `signal`

This page explains some caveats of the `signal` module and provides (currently incomplete) tables about the CPU, GPU and JIT support.

## Caveats

JAX and CuPy provide alternative implementations for some `signal` functions. When such a function is called, a decorator decides which implementation to use by inspecting the xp parameter.

Hence, there can be, especially during CI testing, discrepancies in behavior between the default NumPy-based implementation and the JAX and CuPy backends. Skipping the incompatible backends in unit tests, as described in the Adding tests section, is the currently recommended workaround.

The functions are decorated by the code in file `scipy/signal/_support_alternative_backends.py`:

      1import functools
      2import types
      3from scipy._lib._array_api import (
      4    is_cupy, is_jax, scipy_namespace_for, SCIPY_ARRAY_API, xp_capabilities
      5)
      6
      7from ._signal_api import *   # noqa: F403
      8from . import _signal_api
      9from . import _delegators
     10__all__ = _signal_api.__all__
     11
     12
     13MODULE_NAME = 'signal'
     14
     15# jax.scipy.signal has only partial coverage of scipy.signal, so we keep the list
     16# of functions we can delegate to JAX
     17# https://jax.readthedocs.io/en/latest/jax.scipy.html
     18JAX_SIGNAL_FUNCS = [
     19    'fftconvolve', 'convolve', 'convolve2d', 'correlate', 'correlate2d',
     20    'csd', 'detrend', 'istft', 'welch'
     21]
     22
     23# some cupyx.scipy.signal functions are incompatible with their scipy counterparts
     24CUPY_BLACKLIST = [
     25    'abcd_normalize', 'bessel', 'besselap', 'envelope', 'get_window', 'lfilter_zi',
     26    'sosfilt_zi', 'remez',
     27]
     28
     29# freqz_sos is a sosfreqz rename, and cupy does not have the new name yet (in v13.x)
     30CUPY_RENAMES = {'freqz_sos': 'sosfreqz'}
     31
     32
     33def delegate_xp(delegator, module_name):
     34    def inner(func):
     35        @functools.wraps(func)
     36        def wrapper(*args, **kwds):
     37            try:
     38                xp = delegator(*args, **kwds)
     39            except TypeError:
     40                # object arrays
     41                if func.__name__ == "tf2ss":
     42                    import numpy as np
     43                    xp = np
     44                else:
     45                    raise
     46
     47            # try delegating to a cupyx/jax namesake
     48            if is_cupy(xp) and func.__name__ not in CUPY_BLACKLIST:
     49                func_name = CUPY_RENAMES.get(func.__name__, func.__name__)
     50
     51                # https://github.com/cupy/cupy/issues/8336
     52                import importlib
     53                cupyx_module = importlib.import_module(f"cupyx.scipy.{module_name}")
     54                cupyx_func = getattr(cupyx_module, func_name)
     55                kwds.pop('xp', None)
     56                return cupyx_func(*args, **kwds)
     57            elif is_jax(xp) and func.__name__ in JAX_SIGNAL_FUNCS:
     58                spx = scipy_namespace_for(xp)
     59                jax_module = getattr(spx, module_name)
     60                jax_func = getattr(jax_module, func.__name__)
     61                kwds.pop('xp', None)
     62                return jax_func(*args, **kwds)
     63            else:
     64                # the original function
     65                return func(*args, **kwds)
     66        return wrapper
     67    return inner
     68
     69
     70# Although most of these functions currently exist in CuPy and some in JAX,
     71# there are no alternative backend tests for any of them in the current
     72# test suite. Each will be documented as np_only until tests are added.
     73untested = {
     74    "argrelextrema",
     75    "argrelmax",
     76    "argrelmin",
     77    "band_stop_obj",
     78    "bode",
     79    "check_NOLA",
     80    "chirp",
     81    "coherence",
     82    "csd",
     83    "czt",
     84    "czt_points",
     85    "dbode",
     86    "dfreqresp",
     87    "dlsim",
     88    "dstep",
     89    "find_peaks",
     90    "find_peaks_cwt",
     91    "freqresp",
     92    "gausspulse",
     93    "iirdesign", # There's no reason this shouldn't work. It just needs tests.
     94    "istft",
     95    "lombscargle",
     96    "lsim",
     97    "max_len_seq",
     98    "peak_prominences",
     99    "peak_widths",
    100    "periodogram",
    101    "place_poles",
    102    "sawtooth",
    103    "sepfir2d",
    104    "ss2tf",
    105    "ss2zpk",
    106    "step",
    107    "sweep_poly",
    108    "symiirorder1",
    109    "symiirorder2",
    110    "tf2ss",
    111    "unit_impulse",
    112    "welch",
    113    "zoom_fft",
    114    "zpk2ss",
    115}
    116
    117
    118def get_default_capabilities(func_name, delegator):
    119    if delegator is None or func_name in untested:
    120        return xp_capabilities(np_only=True)
    121    return xp_capabilities()
    122
    123bilinear_extra_note = \
    124    """CuPy does not accept complex inputs.
    125
    126    """
    127
    128uses_choose_conv_extra_note = \
    129    """CuPy does not support inputs with ``ndim>1`` when ``method="auto"``
    130    but does support higher dimensional arrays for ``method="direct"``
    131    and ``method="fft"``.
    132
    133    """
    134
    135resample_poly_extra_note = \
    136    """CuPy only supports ``padtype="constant"``.
    137
    138    """
    139
    140upfirdn_extra_note = \
    141    """CuPy only supports ``mode="constant"`` and ``cval=0.0``.
    142
    143    """
    144
    145xord_extra_note = \
    146    """The ``torch`` backend on GPU does not support the case where
    147    `wp` and `ws` specify a Bandstop filter.
    148
    149    """
    150
    151convolve2d_extra_note = \
    152    """The JAX backend only supports ``boundary="fill"`` and ``fillvalue=0``.
    153
    154    """
    155
    156zpk2tf_extra_note = \
    157    """The CuPy and JAX backends both support only 1d input.
    158
    159    """
    160
    161abcd_normalize_extra_note = \
    162    """The result dtype when all array inputs are of integer dtype is the
    163    backend's current default floating point dtype.
    164
    165    """
    166
    167capabilities_overrides = {
    168    "abcd_normalize": xp_capabilities(extra_note=abcd_normalize_extra_note),
    169    "bessel": xp_capabilities(cpu_only=True, jax_jit=False, allow_dask_compute=True),
    170    "bilinear": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    171                                jax_jit=False, allow_dask_compute=True,
    172                                reason="Uses np.polynomial.Polynomial",
    173                                extra_note=bilinear_extra_note),
    174    "bilinear_zpk": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    175                                    jax_jit=False, allow_dask_compute=True),
    176    "butter": xp_capabilities(cpu_only=True, exceptions=["cupy"], jax_jit=False,
    177                              allow_dask_compute=True),
    178    "buttord": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    179                               jax_jit=False, allow_dask_compute=True,
    180                               extra_note=xord_extra_note),
    181    "cheb1ord": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    182                                jax_jit=False, allow_dask_compute=True,
    183                                extra_note=xord_extra_note),
    184    "cheb2ord": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    185                                jax_jit=False, allow_dask_compute=True,
    186                                extra_note=xord_extra_note),
    187    "cheby1": xp_capabilities(cpu_only=True, exceptions=["cupy"], jax_jit=False,
    188                              allow_dask_compute=True),
    189
    190    "cheby2": xp_capabilities(cpu_only=True, exceptions=["cupy"], jax_jit=False,
    191                              allow_dask_compute=True),
    192    "cont2discrete": xp_capabilities(np_only=True, exceptions=["cupy"]),
    193    "convolve": xp_capabilities(cpu_only=True, exceptions=["cupy", "jax.numpy"],
    194                                allow_dask_compute=True,
    195                                extra_note=uses_choose_conv_extra_note),
    196    "convolve2d": xp_capabilities(cpu_only=True, exceptions=["cupy", "jax.numpy"],
    197                                  allow_dask_compute=True,
    198                                  extra_note=convolve2d_extra_note),
    199    "correlate": xp_capabilities(cpu_only=True, exceptions=["cupy", "jax.numpy"],
    200                                 allow_dask_compute=True,
    201                                 extra_note=uses_choose_conv_extra_note),
    202    "correlate2d": xp_capabilities(cpu_only=True, exceptions=["cupy", "jax.numpy"],
    203                                   allow_dask_compute=True,
    204                                   extra_note=convolve2d_extra_note),
    205    "correlation_lags": xp_capabilities(out_of_scope=True),
    206    "cspline1d": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    207                                 jax_jit=False, allow_dask_compute=True),
    208    "cspline1d_eval": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    209                                      jax_jit=False, allow_dask_compute=True),
    210    "cspline2d": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    211                                 jax_jit=False, allow_dask_compute=True),
    212    "deconvolve": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    213                                  jax_jit=False, allow_dask_compute=True),
    214    "decimate": xp_capabilities(np_only=True, exceptions=["cupy"]),
    215    "detrend": xp_capabilities(cpu_only=True, exceptions=["cupy", "jax.numpy"],
    216                               allow_dask_compute=True),
    217    "dimpulse": xp_capabilities(np_only=True, exceptions=["cupy"]),
    218    "dlti": xp_capabilities(np_only=True,
    219                            reason="works in CuPy but delegation isn't set up yet"),
    220    "ellip": xp_capabilities(cpu_only=True, exceptions=["cupy"], jax_jit=False,
    221                             allow_dask_compute=True,
    222                             reason="scipy.special.ellipk"),
    223    "ellipord": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    224                                jax_jit=False, allow_dask_compute=True,
    225                                reason="scipy.special.ellipk"),
    226    "findfreqs": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    227                                 jax_jit=False, allow_dask_compute=True),
    228    "firls": xp_capabilities(cpu_only=True, allow_dask_compute=True, jax_jit=False,
    229                             reason="lstsq"),
    230    "firwin": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    231                              jax_jit=False, allow_dask_compute=True),
    232    "firwin2": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    233                               jax_jit=False, allow_dask_compute=True,
    234                               reason="firwin uses np.interp"),
    235    "fftconvolve": xp_capabilities(cpu_only=True,
    236                                   exceptions=["cupy", "jax.numpy", "torch"]),
    237    "freqs": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    238                             jax_jit=False, allow_dask_compute=True),
    239    "freqs_zpk": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    240                                 jax_jit=False, allow_dask_compute=True),
    241    "freqz": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    242                             jax_jit=False, allow_dask_compute=True),
    243    "freqz_sos": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    244                                 jax_jit=False, allow_dask_compute=True),
    245    "group_delay": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    246                                   jax_jit=False, allow_dask_compute=True),
    247    "invres": xp_capabilities(np_only=True, exceptions=["cupy"]),
    248    "invresz": xp_capabilities(np_only=True, exceptions=["cupy"]),
    249    "iircomb": xp_capabilities(xfail_backends=[("jax.numpy", "inaccurate")]),
    250    "iirfilter": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    251                                 jax_jit=False, allow_dask_compute=True),
    252    "kaiser_atten": xp_capabilities(
    253        out_of_scope=True, reason="scalars in, scalars out"
    254    ),
    255    "kaiser_beta": xp_capabilities(out_of_scope=True, reason="scalars in, scalars out"),
    256    "kaiserord": xp_capabilities(out_of_scope=True, reason="scalars in, scalars out"),
    257    "lfilter": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    258                               allow_dask_compute=True, jax_jit=False),
    259    "lfilter_zi": xp_capabilities(cpu_only=True, allow_dask_compute=True,
    260                                  jax_jit=False),
    261    "lfiltic": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    262                               allow_dask_compute=True),
    263    "lp2bp": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    264                             allow_dask_compute=True, jax_jit=False),
    265    "lp2bp_zpk": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    266                                 allow_dask_compute=True, jax_jit=False),
    267    "lp2bs": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    268                             allow_dask_compute=True, jax_jit=False),
    269    "lp2bs_zpk": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    270                                 allow_dask_compute=True, jax_jit=False),
    271    "lp2lp": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    272                             allow_dask_compute=True, jax_jit=False),
    273    "lp2lp_zpk": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    274                                 allow_dask_compute=True, jax_jit=False),
    275    "lp2hp": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    276                             allow_dask_compute=True, jax_jit=False),
    277    "lp2hp_zpk": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    278                                 allow_dask_compute=True, jax_jit=False),
    279    "lti": xp_capabilities(np_only=True,
    280                            reason="works in CuPy but delegation isn't set up yet"),
    281    "medfilt": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    282                               allow_dask_compute=True, jax_jit=False,
    283                               reason="uses scipy.ndimage.rank_filter"),
    284    "medfilt2d": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    285                                 allow_dask_compute=True, jax_jit=False,
    286                                 reason="c extension module"),
    287    "minimum_phase": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    288                                     allow_dask_compute=True, jax_jit=False),
    289    "normalize": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    290                                 jax_jit=False, allow_dask_compute=True),
    291    "oaconvolve": xp_capabilities(
    292        cpu_only=True, exceptions=["cupy", "torch"],
    293        xfail_backends=[("dask.array", "wrong answer")],
    294    ),
    295    "order_filter": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    296                                    allow_dask_compute=True, jax_jit=False,
    297                                    reason="uses scipy.ndimage.rank_filter"),
    298    "qspline1d": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    299                                 jax_jit=False, allow_dask_compute=True),
    300    "qspline1d_eval": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    301                                      jax_jit=False, allow_dask_compute=True),
    302    "qspline2d": xp_capabilities(np_only=True, exceptions=["cupy"]),
    303    "remez": xp_capabilities(cpu_only=True, allow_dask_compute=True, jax_jit=False),
    304    "resample": xp_capabilities(
    305        cpu_only=True, exceptions=["cupy"],
    306        skip_backends=[
    307            ("dask.array", "XXX something in dask"),
    308            ("jax.numpy", "XXX: immutable arrays"),
    309        ]
    310    ),
    311    "resample_poly": xp_capabilities(
    312        cpu_only=True, exceptions=["cupy"],
    313        jax_jit=False, skip_backends=[("dask.array", "XXX something in dask")],
    314        extra_note=resample_poly_extra_note,
    315    ),
    316    "residue": xp_capabilities(np_only=True, exceptions=["cupy"]),
    317    "residuez": xp_capabilities(np_only=True, exceptions=["cupy"]),
    318    "savgol_filter": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    319                                     jax_jit=False,
    320                                     reason="convolve1d is cpu-only"),
    321    "sawtooth": xp_capabilities(jax_jit=False,
    322                                skip_backends=[("dask.array", "dask tests fail")]),
    323    "sepfir2d": xp_capabilities(np_only=True),
    324    "sos2zpk": xp_capabilities(cpu_only=True, exceptions=["cupy"], jax_jit=False,
    325                               allow_dask_compute=True),
    326    "sos2tf": xp_capabilities(cpu_only=True, exceptions=["cupy"], jax_jit=False,
    327                              allow_dask_compute=True),
    328    "sosfilt": xp_capabilities(cpu_only=True, exceptions=["cupy"], jax_jit=False,
    329                               allow_dask_compute=True),
    330    "sosfilt_zi": xp_capabilities(cpu_only=True, allow_dask_compute=True,
    331                                  jax_jit=False),
    332    "sosfiltfilt": xp_capabilities(
    333        cpu_only=True, exceptions=["cupy"],
    334        skip_backends=[
    335            (
    336                "dask.array",
    337                "sosfiltfilt directly sets shape attributes on arrays"
    338                " which dask doesn't like"
    339            ),
    340            ("torch", "negative strides"),
    341            ("jax.numpy", "sosfilt works in-place"),
    342        ],
    343    ),
    344    "sosfreqz": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    345                                jax_jit=False, allow_dask_compute=True),
    346    "spline_filter": xp_capabilities(cpu_only=True, exceptions=["cupy"],
    347                                     jax_jit=False, allow_dask_compute=True),
    348    "tf2sos": xp_capabilities(cpu_only=True, exceptions=["cupy"], jax_jit=False,
    349                              allow_dask_compute=True),
    350    "tf2zpk": xp_capabilities(cpu_only=True, exceptions=["cupy"], jax_jit=False,
    351                              allow_dask_compute=True),
    352    "unique_roots": xp_capabilities(np_only=True, exceptions=["cupy"]),
    353    "upfirdn": xp_capabilities(cpu_only=True, exceptions=["cupy"], jax_jit=False,
    354                               allow_dask_compute=True,
    355                               reason="Cython implementation",
    356                               extra_note=upfirdn_extra_note),
    357    "vectorstrength": xp_capabilities(cpu_only=True, exceptions=["cupy", "torch"],
    358                                      allow_dask_compute=True, jax_jit=False),
    359    "wiener": xp_capabilities(cpu_only=True, exceptions=["cupy", "jax.numpy"],
    360                              allow_dask_compute=True, jax_jit=False,
    361                              reason="uses scipy.signal.correlate"),
    362    "zpk2sos": xp_capabilities(cpu_only=True, exceptions=["cupy"], jax_jit=False,
    363                               allow_dask_compute=True),
    364    "zpk2tf": xp_capabilities(cpu_only=True, exceptions=["cupy"], jax_jit=False,
    365                              allow_dask_compute=True,
    366                              extra_note=zpk2tf_extra_note),
    367    "spectrogram": xp_capabilities(out_of_scope=True),  # legacy
    368    "stft": xp_capabilities(out_of_scope=True),  # legacy
    369    "istft": xp_capabilities(out_of_scope=True),  # legacy
    370    "check_COLA": xp_capabilities(out_of_scope=True),  # legacy
    371}
    372
    373
    374# ### decorate ###
    375for obj_name in _signal_api.__all__:
    376    bare_obj = getattr(_signal_api, obj_name)
    377    delegator = getattr(_delegators, obj_name + "_signature", None)
    378
    379    if SCIPY_ARRAY_API and delegator is not None:
    380        f = delegate_xp(delegator, MODULE_NAME)(bare_obj)
    381    else:
    382        f = bare_obj
    383
    384    if not isinstance(f, types.ModuleType):
    385        capabilities = capabilities_overrides.get(
    386            obj_name, get_default_capabilities(obj_name, delegator)
    387        )
    388        f = capabilities(f)  # pyrefly:ignore[not-callable]
    389
    390    # add the decorated function to the namespace, to be imported in __init__.py
    391    vars()[obj_name] = f

Note that a function will only be decorated if the environment variable `SCIPY_ARRAY_API` is set and its signature is listed in the file `scipy/signal/_delegators.py`. E.g., for `firwin`, the signature function looks like this:

    339def firwin_signature(numtaps, cutoff, *args, **kwds):
    340    if isinstance(cutoff, int | float):
    341        xp = np_compat
    342    else:
    343        xp = array_namespace(cutoff)
    344    return xp

## Support on CPU

Legend

✔️ = supported

✖ = unsupported

N/A = out-of-scope

function/class | torch | jax | dask
--- | --- | --- | ---
CZT | ✖ | ✖ | ✖
ShortTimeFFT | ✖ | ✖ | ✖
StateSpace | ✖ | ✖ | ✖
TransferFunction | ✖ | ✖ | ✖
ZerosPolesGain | ✖ | ✖ | ✖
ZoomFFT | ✖ | ✖ | ✖
abcd_normalize | ✔️ | ✔️ | ✔️
argrelextrema | ✖ | ✖ | ✖
argrelmax | ✖ | ✖ | ✖
argrelmin | ✖ | ✖ | ✖
band_stop_obj | ✖ | ✖ | ✖
bessel | ✔️ | ✔️ | ✔️
besselap | ✔️ | ✔️ | ✔️
bilinear | ✔️ | ✔️ | ✔️
bilinear_zpk | ✔️ | ✔️ | ✔️
bode | ✖ | ✖ | ✖
buttap | ✔️ | ✔️ | ✔️
butter | ✔️ | ✔️ | ✔️
buttord | ✔️ | ✔️ | ✔️
cheb1ap | ✔️ | ✔️ | ✔️
cheb1ord | ✔️ | ✔️ | ✔️
cheb2ap | ✔️ | ✔️ | ✔️
cheb2ord | ✔️ | ✔️ | ✔️
cheby1 | ✔️ | ✔️ | ✔️
cheby2 | ✔️ | ✔️ | ✔️
check_COLA | N/A | N/A | N/A
check_NOLA | ✖ | ✖ | ✖
chirp | ✖ | ✖ | ✖
choose_conv_method | ✔️ | ✔️ | ✔️
closest_STFT_dual_window | ✖ | ✖ | ✖
coherence | ✖ | ✖ | ✖
cont2discrete | ✖ | ✖ | ✖
convolve | ✔️ | ✔️ | ✔️
convolve2d | ✔️ | ✔️ | ✔️
correlate | ✔️ | ✔️ | ✔️
correlate2d | ✔️ | ✔️ | ✔️
correlation_lags | N/A | N/A | N/A
csd | ✖ | ✖ | ✖
cspline1d | ✔️ | ✔️ | ✔️
cspline1d_eval | ✔️ | ✔️ | ✔️
cspline2d | ✔️ | ✔️ | ✔️
czt | ✖ | ✖ | ✖
czt_points | ✖ | ✖ | ✖
dbode | ✖ | ✖ | ✖
decimate | ✖ | ✖ | ✖
deconvolve | ✔️ | ✔️ | ✔️
detrend | ✔️ | ✔️ | ✔️
dfreqresp | ✖ | ✖ | ✖
dimpulse | ✖ | ✖ | ✖
dlsim | ✖ | ✖ | ✖
dlti | ✖ | ✖ | ✖
dstep | ✖ | ✖ | ✖
ellip | ✔️ | ✔️ | ✔️
ellipap | ✔️ | ✔️ | ✔️
ellipord | ✔️ | ✔️ | ✔️
envelope | ✔️ | ✔️ | ✔️
fftconvolve | ✔️ | ✔️ | ✔️
filtfilt | ✔️ | ✔️ | ✔️
find_peaks | ✖ | ✖ | ✖
find_peaks_cwt | ✖ | ✖ | ✖
findfreqs | ✔️ | ✔️ | ✔️
firls | ✔️ | ✔️ | ✔️
firwin | ✔️ | ✔️ | ✔️
firwin2 | ✔️ | ✔️ | ✔️
firwin_2d | ✖ | ✖ | ✖
freqresp | ✖ | ✖ | ✖
freqs | ✔️ | ✔️ | ✔️
freqs_zpk | ✔️ | ✔️ | ✔️
freqz | ✔️ | ✔️ | ✔️
freqz_sos | ✔️ | ✔️ | ✔️
freqz_zpk | ✔️ | ✔️ | ✔️
gammatone | ✔️ | ✔️ | ✔️
gauss_spline | ✔️ | ✔️ | ✔️
gausspulse | ✖ | ✖ | ✖
get_window | ✔️ | ✔️ | ✔️
group_delay | ✔️ | ✔️ | ✔️
hilbert | ✔️ | ✔️ | ✔️
hilbert2 | ✔️ | ✔️ | ✔️
iircomb | ✔️ | ✖ | ✔️
iirdesign | ✖ | ✖ | ✖
iirfilter | ✔️ | ✔️ | ✔️
iirnotch | ✔️ | ✔️ | ✔️
iirpeak | ✔️ | ✔️ | ✔️
impulse | ✔️ | ✔️ | ✔️
invres | ✖ | ✖ | ✖
invresz | ✖ | ✖ | ✖
istft | N/A | N/A | N/A
kaiser_atten | N/A | N/A | N/A
kaiser_beta | N/A | N/A | N/A
kaiserord | N/A | N/A | N/A
lfilter | ✔️ | ✔️ | ✔️
lfilter_zi | ✔️ | ✔️ | ✔️
lfiltic | ✔️ | ✔️ | ✔️
lombscargle | ✖ | ✖ | ✖
lp2bp | ✔️ | ✔️ | ✔️
lp2bp_zpk | ✔️ | ✔️ | ✔️
lp2bs | ✔️ | ✔️ | ✔️
lp2bs_zpk | ✔️ | ✔️ | ✔️
lp2hp | ✔️ | ✔️ | ✔️
lp2hp_zpk | ✔️ | ✔️ | ✔️
lp2lp | ✔️ | ✔️ | ✔️
lp2lp_zpk | ✔️ | ✔️ | ✔️
lsim | ✖ | ✖ | ✖
lti | ✖ | ✖ | ✖
max_len_seq | ✖ | ✖ | ✖
medfilt | ✔️ | ✔️ | ✔️
medfilt2d | ✔️ | ✔️ | ✔️
minimum_phase | ✔️ | ✔️ | ✔️
normalize | ✔️ | ✔️ | ✔️
oaconvolve | ✔️ | ✔️ | ✖
order_filter | ✔️ | ✔️ | ✔️
peak_prominences | ✖ | ✖ | ✖
peak_widths | ✖ | ✖ | ✖
periodogram | ✖ | ✖ | ✖
place_poles | ✖ | ✖ | ✖
qspline1d | ✔️ | ✔️ | ✔️
qspline1d_eval | ✔️ | ✔️ | ✔️
qspline2d | ✖ | ✖ | ✖
remez | ✔️ | ✔️ | ✔️
resample | ✔️ | ✖ | ✖
resample_poly | ✔️ | ✔️ | ✖
residue | ✖ | ✖ | ✖
residuez | ✖ | ✖ | ✖
savgol_coeffs | ✔️ | ✔️ | ✔️
savgol_filter | ✔️ | ✔️ | ✔️
sawtooth | ✔️ | ✔️ | ✖
sepfir2d | ✖ | ✖ | ✖
sos2tf | ✔️ | ✔️ | ✔️
sos2zpk | ✔️ | ✔️ | ✔️
sosfilt | ✔️ | ✔️ | ✔️
sosfilt_zi | ✔️ | ✔️ | ✔️
sosfiltfilt | ✖ | ✖ | ✖
sosfreqz | ✔️ | ✔️ | ✔️
spectrogram | N/A | N/A | N/A
spline_filter | ✔️ | ✔️ | ✔️
square | ✔️ | ✔️ | ✔️
ss2tf | ✖ | ✖ | ✖
ss2zpk | ✖ | ✖ | ✖
step | ✖ | ✖ | ✖
stft | N/A | N/A | N/A
sweep_poly | ✖ | ✖ | ✖
symiirorder1 | ✖ | ✖ | ✖
symiirorder2 | ✖ | ✖ | ✖
tf2sos | ✔️ | ✔️ | ✔️
tf2ss | ✖ | ✖ | ✖
tf2zpk | ✔️ | ✔️ | ✔️
unique_roots | ✖ | ✖ | ✖
unit_impulse | ✖ | ✖ | ✖
upfirdn | ✔️ | ✔️ | ✔️
vectorstrength | ✔️ | ✔️ | ✔️
welch | ✖ | ✖ | ✖
whittaker_henderson | ✖ | ✖ | ✖
wiener | ✔️ | ✔️ | ✔️
zoom_fft | ✖ | ✖ | ✖
zpk2sos | ✔️ | ✔️ | ✔️
zpk2ss | ✖ | ✖ | ✖
zpk2tf | ✔️ | ✔️ | ✔️

## Support on GPU

Legend

✔️ = supported

✖ = unsupported

N/A = out-of-scope

function/class | cupy | torch | jax
--- | --- | --- | ---
CZT | ✖ | ✖ | ✖
ShortTimeFFT | ✖ | ✖ | ✖
StateSpace | ✖ | ✖ | ✖
TransferFunction | ✖ | ✖ | ✖
ZerosPolesGain | ✖ | ✖ | ✖
ZoomFFT | ✖ | ✖ | ✖
abcd_normalize | ✔️ | ✔️ | ✔️
argrelextrema | ✖ | ✖ | ✖
argrelmax | ✖ | ✖ | ✖
argrelmin | ✖ | ✖ | ✖
band_stop_obj | ✖ | ✖ | ✖
bessel | ✖ | ✖ | ✖
besselap | ✔️ | ✔️ | ✔️
bilinear | ✔️ | ✖ | ✖
bilinear_zpk | ✔️ | ✔️ | ✖
bode | ✖ | ✖ | ✖
buttap | ✔️ | ✔️ | ✔️
butter | ✔️ | ✖ | ✖
buttord | ✔️ | ✔️ | ✖
cheb1ap | ✔️ | ✔️ | ✔️
cheb1ord | ✔️ | ✔️ | ✖
cheb2ap | ✔️ | ✔️ | ✔️
cheb2ord | ✔️ | ✔️ | ✖
cheby1 | ✔️ | ✖ | ✖
cheby2 | ✔️ | ✖ | ✖
check_COLA | N/A | N/A | N/A
check_NOLA | ✖ | ✖ | ✖
chirp | ✖ | ✖ | ✖
choose_conv_method | ✔️ | ✔️ | ✔️
closest_STFT_dual_window | ✖ | ✖ | ✖
coherence | ✖ | ✖ | ✖
cont2discrete | ✔️ | ✖ | ✖
convolve | ✔️ | ✖ | ✔️
convolve2d | ✔️ | ✖ | ✔️
correlate | ✔️ | ✖ | ✔️
correlate2d | ✔️ | ✖ | ✔️
correlation_lags | N/A | N/A | N/A
csd | ✖ | ✖ | ✖
cspline1d | ✔️ | ✖ | ✖
cspline1d_eval | ✔️ | ✖ | ✖
cspline2d | ✔️ | ✖ | ✖
czt | ✖ | ✖ | ✖
czt_points | ✖ | ✖ | ✖
dbode | ✖ | ✖ | ✖
decimate | ✔️ | ✖ | ✖
deconvolve | ✔️ | ✖ | ✖
detrend | ✔️ | ✖ | ✔️
dfreqresp | ✖ | ✖ | ✖
dimpulse | ✔️ | ✖ | ✖
dlsim | ✖ | ✖ | ✖
dlti | ✖ | ✖ | ✖
dstep | ✖ | ✖ | ✖
ellip | ✔️ | ✖ | ✖
ellipap | ✔️ | ✔️ | ✔️
ellipord | ✔️ | ✖ | ✖
envelope | ✔️ | ✔️ | ✔️
fftconvolve | ✔️ | ✔️ | ✔️
filtfilt | ✔️ | ✔️ | ✔️
find_peaks | ✖ | ✖ | ✖
find_peaks_cwt | ✖ | ✖ | ✖
findfreqs | ✔️ | ✔️ | ✖
firls | ✖ | ✖ | ✖
firwin | ✔️ | ✔️ | ✖
firwin2 | ✔️ | ✖ | ✖
firwin_2d | ✖ | ✖ | ✖
freqresp | ✖ | ✖ | ✖
freqs | ✔️ | ✔️ | ✖
freqs_zpk | ✔️ | ✔️ | ✖
freqz | ✔️ | ✔️ | ✖
freqz_sos | ✔️ | ✔️ | ✖
freqz_zpk | ✔️ | ✔️ | ✔️
gammatone | ✔️ | ✔️ | ✔️
gauss_spline | ✔️ | ✔️ | ✔️
gausspulse | ✖ | ✖ | ✖
get_window | ✔️ | ✔️ | ✔️
group_delay | ✔️ | ✖ | ✖
hilbert | ✔️ | ✔️ | ✔️
hilbert2 | ✔️ | ✔️ | ✔️
iircomb | ✔️ | ✔️ | ✖
iirdesign | ✖ | ✖ | ✖
iirfilter | ✔️ | ✔️ | ✖
iirnotch | ✔️ | ✔️ | ✔️
iirpeak | ✔️ | ✔️ | ✔️
impulse | ✔️ | ✔️ | ✔️
invres | ✔️ | ✖ | ✖
invresz | ✔️ | ✖ | ✖
istft | N/A | N/A | N/A
kaiser_atten | N/A | N/A | N/A
kaiser_beta | N/A | N/A | N/A
kaiserord | N/A | N/A | N/A
lfilter | ✔️ | ✖ | ✖
lfilter_zi | ✖ | ✖ | ✖
lfiltic | ✔️ | ✖ | ✖
lombscargle | ✖ | ✖ | ✖
lp2bp | ✔️ | ✔️ | ✖
lp2bp_zpk | ✔️ | ✔️ | ✖
lp2bs | ✔️ | ✔️ | ✖
lp2bs_zpk | ✔️ | ✔️ | ✖
lp2hp | ✔️ | ✔️ | ✖
lp2hp_zpk | ✔️ | ✔️ | ✖
lp2lp | ✔️ | ✔️ | ✖
lp2lp_zpk | ✔️ | ✔️ | ✖
lsim | ✖ | ✖ | ✖
lti | ✖ | ✖ | ✖
max_len_seq | ✖ | ✖ | ✖
medfilt | ✔️ | ✖ | ✖
medfilt2d | ✔️ | ✖ | ✖
minimum_phase | ✔️ | ✔️ | ✖
normalize | ✔️ | ✔️ | ✖
oaconvolve | ✔️ | ✔️ | ✖
order_filter | ✔️ | ✖ | ✖
peak_prominences | ✖ | ✖ | ✖
peak_widths | ✖ | ✖ | ✖
periodogram | ✖ | ✖ | ✖
place_poles | ✖ | ✖ | ✖
qspline1d | ✔️ | ✖ | ✖
qspline1d_eval | ✔️ | ✖ | ✖
qspline2d | ✔️ | ✖ | ✖
remez | ✖ | ✖ | ✖
resample | ✔️ | ✖ | ✖
resample_poly | ✔️ | ✖ | ✖
residue | ✔️ | ✖ | ✖
residuez | ✔️ | ✖ | ✖
savgol_coeffs | ✔️ | ✔️ | ✔️
savgol_filter | ✔️ | ✖ | ✖
sawtooth | ✔️ | ✔️ | ✔️
sepfir2d | ✖ | ✖ | ✖
sos2tf | ✔️ | ✖ | ✖
sos2zpk | ✔️ | ✖ | ✖
sosfilt | ✔️ | ✖ | ✖
sosfilt_zi | ✖ | ✖ | ✖
sosfiltfilt | ✔️ | ✖ | ✖
sosfreqz | ✔️ | ✔️ | ✖
spectrogram | N/A | N/A | N/A
spline_filter | ✔️ | ✖ | ✖
square | ✔️ | ✔️ | ✔️
ss2tf | ✖ | ✖ | ✖
ss2zpk | ✖ | ✖ | ✖
step | ✖ | ✖ | ✖
stft | N/A | N/A | N/A
sweep_poly | ✖ | ✖ | ✖
symiirorder1 | ✖ | ✖ | ✖
symiirorder2 | ✖ | ✖ | ✖
tf2sos | ✔️ | ✖ | ✖
tf2ss | ✖ | ✖ | ✖
tf2zpk | ✔️ | ✖ | ✖
unique_roots | ✔️ | ✖ | ✖
unit_impulse | ✖ | ✖ | ✖
upfirdn | ✔️ | ✖ | ✖
vectorstrength | ✔️ | ✔️ | ✖
welch | ✖ | ✖ | ✖
whittaker_henderson | ✖ | ✖ | ✖
wiener | ✔️ | ✖ | ✔️
zoom_fft | ✖ | ✖ | ✖
zpk2sos | ✔️ | ✖ | ✖
zpk2ss | ✖ | ✖ | ✖
zpk2tf | ✔️ | ✖ | ✖

## Support with JIT

Legend

✔️ = supported

✖ = unsupported

N/A = out-of-scope

function/class | jax
--- | ---
CZT | ✖
ShortTimeFFT | ✖
StateSpace | ✖
TransferFunction | ✖
ZerosPolesGain | ✖
ZoomFFT | ✖
abcd_normalize | ✔️
argrelextrema | ✖
argrelmax | ✖
argrelmin | ✖
band_stop_obj | ✖
bessel | ✖
besselap | ✔️
bilinear | ✖
bilinear_zpk | ✖
bode | ✖
buttap | ✔️
butter | ✖
buttord | ✖
cheb1ap | ✔️
cheb1ord | ✖
cheb2ap | ✔️
cheb2ord | ✖
cheby1 | ✖
cheby2 | ✖
check_COLA | N/A
check_NOLA | ✖
chirp | ✖
choose_conv_method | ✔️
closest_STFT_dual_window | ✖
coherence | ✖
cont2discrete | ✖
convolve | ✔️
convolve2d | ✔️
correlate | ✔️
correlate2d | ✔️
correlation_lags | N/A
csd | ✖
cspline1d | ✖
cspline1d_eval | ✖
cspline2d | ✖
czt | ✖
czt_points | ✖
dbode | ✖
decimate | ✖
deconvolve | ✖
detrend | ✔️
dfreqresp | ✖
dimpulse | ✖
dlsim | ✖
dlti | ✖
dstep | ✖
ellip | ✖
ellipap | ✔️
ellipord | ✖
envelope | ✔️
fftconvolve | ✔️
filtfilt | ✔️
find_peaks | ✖
find_peaks_cwt | ✖
findfreqs | ✖
firls | ✖
firwin | ✖
firwin2 | ✖
firwin_2d | ✖
freqresp | ✖
freqs | ✖
freqs_zpk | ✖
freqz | ✖
freqz_sos | ✖
freqz_zpk | ✔️
gammatone | ✔️
gauss_spline | ✔️
gausspulse | ✖
get_window | ✔️
group_delay | ✖
hilbert | ✔️
hilbert2 | ✔️
iircomb | ✖
iirdesign | ✖
iirfilter | ✖
iirnotch | ✔️
iirpeak | ✔️
impulse | ✔️
invres | ✖
invresz | ✖
istft | N/A
kaiser_atten | N/A
kaiser_beta | N/A
kaiserord | N/A
lfilter | ✖
lfilter_zi | ✖
lfiltic | ✔️
lombscargle | ✖
lp2bp | ✖
lp2bp_zpk | ✖
lp2bs | ✖
lp2bs_zpk | ✖
lp2hp | ✖
lp2hp_zpk | ✖
lp2lp | ✖
lp2lp_zpk | ✖
lsim | ✖
lti | ✖
max_len_seq | ✖
medfilt | ✖
medfilt2d | ✖
minimum_phase | ✖
normalize | ✖
oaconvolve | ✔️
order_filter | ✖
peak_prominences | ✖
peak_widths | ✖
periodogram | ✖
place_poles | ✖
qspline1d | ✖
qspline1d_eval | ✖
qspline2d | ✖
remez | ✖
resample | ✖
resample_poly | ✖
residue | ✖
residuez | ✖
savgol_coeffs | ✔️
savgol_filter | ✖
sawtooth | ✖
sepfir2d | ✖
sos2tf | ✖
sos2zpk | ✖
sosfilt | ✖
sosfilt_zi | ✖
sosfiltfilt | ✖
sosfreqz | ✖
spectrogram | N/A
spline_filter | ✖
square | ✔️
ss2tf | ✖
ss2zpk | ✖
step | ✖
stft | N/A
sweep_poly | ✖
symiirorder1 | ✖
symiirorder2 | ✖
tf2sos | ✖
tf2ss | ✖
tf2zpk | ✖
unique_roots | ✖
unit_impulse | ✖
upfirdn | ✖
vectorstrength | ✖
welch | ✖
whittaker_henderson | ✖
wiener | ✖
zoom_fft | ✖
zpk2sos | ✖
zpk2ss | ✖
zpk2tf | ✖