aug_wavelength_stretch — Wavelength-axis stretch about its center¶
Group: Augmentation · C ABI: n4m_augmentation_wavelength_stretch_*
Description¶
Random wavelength-axis stretching.
Parameters¶
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API and bindings¶
C ABI (ABI 2): n4m_augmentation_wavelength_stretch_apply · n4m_augmentation_wavelength_stretch_create · n4m_augmentation_wavelength_stretch_destroy. Use the linked public header for the exact signature, configuration, and result handles.
Python (verified public re-export):
from n4m.augmentation.wavelength import WavelengthStretch
Source signature: WavelengthStretch(stretch_lo: float = 0.99, stretch_hi: float = 1.01, wavelengths = None, rng: Optional[PCG64] = None, seed: int = 0).
R: no current source-verified entry point was found for this catalog method.
MATLAB / Octave: no current source-verified entry point was found for this catalog method.
Explanations¶
Bibliographic source¶
No canonical publication specifies this augmenter; it is a wavelength-scale calibration heuristic whose exact interpolation is defined by the source.
Mathematical principle¶
With axis center \(\bar\lambda\), draw \(f_i\sim U(\text{stretch_lo},\text{stretch_hi})\) and evaluate \(X'_i(\lambda_j)=X_i(\bar\lambda+(\lambda_j-\bar\lambda)/f_i)\) using linear interpolation. Factors above one broaden the coordinate scale.
Appropriate uses¶
Simulating small wavelength-scale expansion or compression across instruments.
Limits and validation¶
The deformation is globally affine and cannot represent local calibration error. Endpoint clamping and the implicit unit grid apply as for wavelength shift.
Implementation¶
Python role API n4m.augmentation.wavelength.WavelengthStretch; ABI 2 family n4m_augmentation_wavelength_stretch_{create,apply,destroy}.
The ABI-2 implementation is the n4m_augmentation_wavelength_stretch_* lifecycle in libn4m.
Sources and provenance¶
See also: methods index · interactive dashboard