fix: shift_spectra jaxified

spotter/core.py

@@ -167,24 +167,12 @@ def doppler_shift(theta, phi, period, radius, phase):
 
 
 def shifted_spectra(spectra, shift):
-    n_spectra, n_wavelength = spectra.shape
-
-    # Fourier transform along the wavelength axis (axis=1) for each spectrum independently
-    spectra_ft = np.fft.fft(spectra, axis=1)
-
-    # Generate the frequency indices for each element along the wavelength axis
-    k = np.fft.fftfreq(n_wavelength).reshape(
-        1, -1
-    )  # Shape (1, n_wavelength) to broadcast along rows
-
-    # Compute the phase shift matrix for each element in shift
-    phase_shift = np.exp(-2j * np.pi * k * shift)  # Shape (n_spectra, n_wavelength)
-
-    # Apply the phase shift and inverse Fourier transform
-    shifted = np.fft.ifft(spectra_ft * phase_shift, axis=1)
-
-    # Return the real part, assuming the input was real
-    return np.real(shifted)
+    _, n_wavelength = spectra.shape
+    spectra_ft = jnp.fft.fft(spectra, axis=1)
+    k = np.fft.fftfreq(n_wavelength).reshape(1, -1)
+    phase_shift = jnp.exp(-2j * np.pi * k * shift)
+    shifted = jnp.fft.ifft(spectra_ft * phase_shift, axis=1)
+    return jnp.real(shifted)
 
 
 def integrated_spectrum(N, theta, phi, period, radius, wv, spectra, phase, inc):