When I execute this line of code:
self.forwardDCTSetup = vDSP.DCT(count: 40, transformType: vDSP.DCTTransformType.II)!
I get:
Fatal error: Unexpectedly found nil while unwrapping an Optional value
I am following this tutorial almost exactly: https://developer.apple.com/documentation/accelerate/signal_extraction_from_noise.
The vDSP.DCT
follows the same rules as vDSP_DCT_CreateSetup
with regard to length / count:
The supported values are Length = f * 2**n, where f is 1, 3, 5, or 15 and n is at least 4.
See: https://developer.apple.com/documentation/accelerate/1449930-vdsp_dct_createsetup