Feature request: Add digitize, geomspace, logspace functions from numpy.

[Swoorup]

Add:

• geomspace
• digitize
• logspace

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I only could find linspace in this library. The above would be great to have, working with data binning and histograms.

[dlwh]

digitize is in breeze.stats fwiw:

      val x = DenseVector[Double](-0.5, 0.5, 1.5, 2, 0, 2.5)
      val bins = DenseVector[Double](0.0, 1.0, 2.0)
      val result = digitize(x, bins)
      val desiredResult = DenseVector[Int](0, 1, 2, 2, 0, 3)
      assert(result == desiredResult)