Test failure on aarch64

[effigies]

Detected in conda-forge/nitime-feedstock#33 / conda-forge/nitime-feedstock#34:

___________________________ test_detect_lines_2dmode ___________________________
    def test_detect_lines_2dmode():
        """
        Test multi-sequence operation
        """
    
        N = 1000
    
        sig = np.cos( 2*np.pi*np.arange(N) * 20./N ) + np.random.randn(N) * .01
    
        sig2d = np.row_stack( (sig, sig, sig) )
    
        lines = utils.detect_lines(sig2d, (4, 8), low_bias=True, NFFT=2**12)
    
        npt.assert_(len(lines)==3, 'Detect lines failed multi-sequence mode')
    
        consistent1 = (lines[0][0] == lines[1][0]).all() and \
          (lines[1][0] == lines[2][0]).all()
        consistent2 = (lines[0][1] == lines[1][1]).all() and \
          (lines[1][1] == lines[2][1]).all()
    
>       npt.assert_(consistent1 and consistent2, 'Inconsistent results')
E       AssertionError: Inconsistent results

[larsoner]

Also an issue on macOS arm64:

https://github.com/nipy/nitime/actions/runs/9484648808/job/26134645299?pr=221#step:6:408

      def test_detect_lines():
          """
          Tests detect_lines utility in the reliable low-SNR scenario.
          """

          ...
          f, b = utils.detect_lines(sig, (NW, 2*NW), low_bias=True, NFFT=2**fft_pow)
          h_est = 2*(b[:,None]*np.exp(2j*np.pi*tx*f[:,None])).real
      
  >       npt.assert_(
              len(f) == 3, 'The wrong number of harmonic components were detected'
              )
  E       AssertionError: The wrong number of harmonic components were detected

I'll look to see if the fix is trivial...