Clarification on variable density spiral design

[tomdstone]

Hello, you cite Doug Noll for your variable density spiral design. What particular reference did you use for the formula? I was unable to find it.

sigpy/sigpy/mri/rf/trajgrad.py

Lines 170 to 171 in 5da0e86

	Code and algorithm based on spiralgradlx6 from
	Doug Noll, U. of Michigan BME