|A criticism of certain usage of the Phi-notation|
McManus, D.A. (1963). A criticism of certain usage of the Phi-notation. J. Sediment. Petrol. 33(3): 670-674
In: Journal of Sedimentary Petrology. Society of Economic Paleontologists and Mineralogists (SEPM): Tulsa. ISSN 0022-4472, more
Three serious misuses of the phi-notation have developed since its introduction by Krumbein as the expression of a logarithmic transformation of grain diameters in millimeters. These misuses are: 1) the mistaken correlation of "phi " and "millimeters," 2) the misuse of phi in the expression of values of the standard deviation, and 3) the misuse of "phi-units" as dimensions. These errors have led to a confused interpretation of the meaning of phi . The suggested redefinition of phi as the negative logarithm of the ratio of a grain diameter to a standard diameter is shown to rectify the confusion.