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Merged
jorenham merged 1 commit into from
Jan 7, 2026
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✨ signal: improve cont2discrete #1089

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120 changes: 86 additions & 34 deletions scipy-stubs/signal/_lti_conversion.pyi
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
from typing import Literal, TypeAlias, TypeVar, overload
from typing import Any, Literal, TypeAlias, TypeVar, overload
from typing_extensions import TypeAliasType

import numpy as np
import optype.numpy as onp
Expand All @@ -19,21 +20,28 @@ __all__ = ["abcd_normalize", "cont2discrete", "ss2tf", "ss2zpk", "tf2ss", "zpk2s

###

_ToSystemTF: TypeAlias = tuple[onp.ToComplex2D, onp.ToComplex1D] # (num, den)
_ToSystemZPK: TypeAlias = tuple[onp.ToComplex1D, onp.ToComplex1D, onp.ToFloat] # (z, p, k)
_ToSystemSS: TypeAlias = tuple[onp.ToComplex2D, onp.ToComplex2D, onp.ToComplex2D, onp.ToComplex2D] # (A, B, C, D)

_SafeFloatT = TypeVar("_SafeFloatT", bound=np.float32 | np.float64)
_SafeInexactT = TypeVar("_SafeInexactT", bound=np.float32 | np.float64 | np.complex64 | np.complex128)
_InexactT = TypeVar("_InexactT", bound=npc.inexact, default=npc.inexact)
_Inexact1D: TypeAlias = onp.Array1D[_InexactT]
_Inexact2D: TypeAlias = onp.Array2D[_InexactT]

_SystemTF: TypeAlias = tuple[_Inexact2D[_InexactT], _Inexact1D[_InexactT]]
_SystemZPK: TypeAlias = tuple[_Inexact1D[_InexactT], _Inexact1D[_InexactT], float | np.float64]
_SystemSS: TypeAlias = tuple[_Inexact2D[_InexactT], _Inexact2D[_InexactT], _Inexact2D[_InexactT], _Inexact2D[_InexactT]]
_T = TypeVar("_T")
_Tuple4: TypeAlias = tuple[_T, _T, _T, _T]

_SystemTF: TypeAlias = tuple[onp.Array2D[_InexactT], onp.Array1D[_InexactT]]
_SystemZPK: TypeAlias = tuple[onp.Array1D[_InexactT], onp.Array1D[_InexactT], float | np.float64]
_SystemSS: TypeAlias = tuple[onp.Array2D[_InexactT], onp.Array2D[_InexactT], onp.Array2D[_InexactT], onp.Array2D[_InexactT]]

_DiscretizeMethod: TypeAlias = Literal["gbt", "bilinear", "euler", "backward_diff", "foh", "impulse", "zoh"]
# ty (0.0.9) doens't seem to understand `TypeAlias` with multiple `TypeVar`s
_DiscreteSS = TypeAliasType(
"_DiscreteSS",
tuple[onp.Array2D[_SafeInexactT], onp.Array2D[_SafeInexactT], onp.Array2D[_InexactT], onp.Array2D[_InexactT], float],
type_params=(_SafeInexactT, _InexactT),
)

###

# TODO(@jorenham): refine return dtypes
@overload
def abcd_normalize(
A: onp.ToFloat2D | None = None, B: onp.ToFloat2D | None = None, C: onp.ToFloat2D | None = None, D: onp.ToFloat2D | None = None
Expand All @@ -46,27 +54,27 @@ def abcd_normalize(
D: onp.ToComplex2D | None = None,
) -> _SystemTF: ...

#
# TODO(@jorenham): refine return dtypes
@overload
def tf2ss(num: onp.ToFloat2D, den: onp.ToFloat1D) -> _SystemSS[npc.floating]: ...
@overload
def tf2ss(num: onp.ToComplex2D, den: onp.ToComplex1D) -> _SystemSS: ...

#
# TODO(@jorenham): refine return dtypes
@overload
def ss2tf(
A: onp.ToFloat2D, B: onp.ToFloat2D, C: onp.ToFloat2D, D: onp.ToFloat2D, input: onp.ToInt = 0
) -> _SystemTF[npc.floating]: ...
@overload
def ss2tf(A: onp.ToComplex2D, B: onp.ToComplex2D, C: onp.ToComplex2D, D: onp.ToComplex2D, input: onp.ToInt = 0) -> _SystemTF: ...

#
# TODO(@jorenham): refine return dtypes
@overload
def zpk2ss(z: onp.ToFloat1D, p: onp.ToFloat1D, k: onp.ToFloat) -> _SystemSS[npc.floating]: ...
@overload
def zpk2ss(z: onp.ToComplex1D, p: onp.ToComplex1D, k: onp.ToFloat) -> _SystemSS: ...

#
# TODO(@jorenham): refine return dtypes
@overload
def ss2zpk(
A: onp.ToFloat2D, B: onp.ToFloat2D, C: onp.ToFloat2D, D: onp.ToFloat2D, input: onp.ToInt = 0
Expand All @@ -77,29 +85,73 @@ def ss2zpk(
) -> _SystemZPK: ...

#
@overload
@overload # TransferFunction
def cont2discrete(
system: TransferFunctionContinuous, dt: float, method: _DiscretizeMethod = "zoh", alpha: onp.ToJustFloat | None = None
) -> TransferFunctionDiscrete: ...
@overload
system: TransferFunctionContinuous[_SafeFloatT], dt: float, method: _DiscretizeMethod = "zoh", alpha: float | None = None
) -> TransferFunctionDiscrete[_SafeFloatT]: ...
@overload # ZerosPolesGain
def cont2discrete(
system: ZerosPolesGainContinuous, dt: float, method: _DiscretizeMethod = "zoh", alpha: onp.ToJustFloat | None = None
) -> ZerosPolesGainDiscrete: ...
@overload
system: ZerosPolesGainContinuous[_SafeInexactT, _SafeFloatT],
dt: float,
method: _DiscretizeMethod = "zoh",
alpha: float | None = None,
) -> ZerosPolesGainDiscrete[_SafeInexactT, _SafeFloatT]: ...
@overload # StateSpace
def cont2discrete(
system: StateSpaceContinuous, dt: float, method: _DiscretizeMethod = "zoh", alpha: onp.ToJustFloat | None = None
) -> StateSpaceDiscrete: ...
@overload
def cont2discrete(system: lti, dt: float, method: _DiscretizeMethod = "zoh", alpha: onp.ToJustFloat | None = None) -> dlti: ...
@overload
system: StateSpaceContinuous[_SafeInexactT, _SafeFloatT],
dt: float,
method: _DiscretizeMethod = "zoh",
alpha: float | None = None,
) -> StateSpaceDiscrete[_SafeInexactT, _SafeFloatT]: ...
@overload # lti
def cont2discrete(
system: _ToSystemTF, dt: float, method: _DiscretizeMethod = "zoh", alpha: onp.ToJustFloat | None = None
) -> tuple[_Inexact2D[_InexactT], _Inexact1D[_InexactT], float]: ...
@overload
system: lti[_SafeInexactT, _SafeFloatT], dt: float, method: _DiscretizeMethod = "zoh", alpha: float | None = None
) -> dlti[_SafeInexactT, _SafeFloatT]: ...
@overload # (+f64, +f64)
def cont2discrete(
system: _ToSystemZPK, dt: float, method: _DiscretizeMethod = "zoh", alpha: onp.ToJustFloat | None = None
) -> tuple[_Inexact1D[_InexactT], _Inexact1D[_InexactT], float, float]: ...
@overload
system: tuple[float | onp.ToFloat64_2D, float | onp.ToFloat64_1D],
dt: float,
method: _DiscretizeMethod = "zoh",
alpha: float | None = None,
) -> tuple[onp.Array2D[np.float64], onp.Array1D[np.float64], float]: ...
@overload # (+complex, +complex)
def cont2discrete(
system: tuple[complex | onp.ToComplex2D, complex | onp.ToComplex1D],
dt: float,
method: _DiscretizeMethod = "zoh",
alpha: float | None = None,
) -> tuple[onp.Array2D[np.complex128 | Any], onp.Array1D[np.float64], float]: ...
@overload # (+f64, +f64, float)
def cont2discrete(
system: tuple[float | onp.ToFloat64_1D, float | onp.ToFloat64_1D, float],
dt: float,
method: _DiscretizeMethod = "zoh",
alpha: float | None = None,
) -> tuple[onp.Array1D[np.float64], onp.Array1D[np.float64], np.float64, float]: ...
@overload # (+complex, +complex, complex)
def cont2discrete(
system: tuple[complex | onp.ToComplex1D, complex | onp.ToComplex1D, complex],
dt: float,
method: _DiscretizeMethod = "zoh",
alpha: float | None = None,
) -> tuple[onp.Array1D[np.complex128 | Any], onp.Array1D[np.complex128 | Any], np.complex128 | Any, float]: ...
@overload # (~f64; 4)
def cont2discrete(
system: _Tuple4[onp.ToInt2D | onp.ToJustFloat64_2D], dt: float, method: _DiscretizeMethod = "zoh", alpha: float | None = None
) -> _DiscreteSS[np.float64, np.float64]: ...
@overload # (~f16; 4)
def cont2discrete(
system: _Tuple4[onp.ToJustFloat16_2D], dt: float, method: _DiscretizeMethod = "zoh", alpha: float | None = None
) -> _DiscreteSS[np.float64, np.float16]: ...
@overload # (~f32; 4)
def cont2discrete(
system: _Tuple4[onp.ToJustFloat32_2D], dt: float, method: _DiscretizeMethod = "zoh", alpha: float | None = None
) -> _DiscreteSS[np.float64, np.float32]: ...
@overload # (~c128; 4)
def cont2discrete(
system: _Tuple4[onp.ToJustComplex128_2D], dt: float, method: _DiscretizeMethod = "zoh", alpha: float | None = None
) -> _DiscreteSS[np.complex128, np.complex128]: ...
@overload # (~c64; 4)
def cont2discrete(
system: _ToSystemSS, dt: float, method: _DiscretizeMethod = "zoh", alpha: onp.ToJustFloat | None = None
) -> tuple[_Inexact2D[_InexactT], _Inexact2D[_InexactT], _Inexact2D[_InexactT], _Inexact2D[_InexactT], float]: ...
system: _Tuple4[onp.ToJustComplex64_2D], dt: float, method: _DiscretizeMethod = "zoh", alpha: float | None = None
) -> _DiscreteSS[np.complex128, np.complex64]: ...