aliases2(basis [,effect:vec] [,length:j]), REAL matrix basis of alias generators, REAL vector vec of 0's and 1's, positive integer j |

aliases2(basis) finds all aliases of I in a 2^(k-p) fractional factorial and returns a CHARACTER vector of these aliases as its value. k must be no larger than 25, and factors are labeled A, B, C, ..., H, J, ... Z (skipping I). The p x k matrix basis contains the generators for the aliasing, one row for each generator and one column for each factor in the design. The elements in basis are 0, -1, or 1. A nonzero entry indicates that a factor is present in the generator for that row. The sign of a generator is the product of the signs of the nonzero elements of the generator. For example, 1 0 1 0 0 -1 means -ACF is a generator (alias of I). If basis is a (column) vector, it is changed to a row vector (1 by k matrix) before proceding. aliases2(basis,effect:vec) returns the aliases of vec, a vector of k 0s and 1s that specifies an effect. aliases2(basis [,effect:vec],length:j) does the same but returns only aliases of length j. Examples: Cmd> print(format:"2.0f",b) # Matrix b is 2x5, so 2^(5-2) design b: (1,1) 1 1 1 0 0 [ABC is a generator] (2,1) 0 0 1 1 -1 [-CDE is a generator] Cmd> aliases2(b) # aliases of I (1) "I" (2) "ABC" (3) "-CDE" (4) "-ABDE" Cmd> aliases2(b,length:3) # length 3 aliases of I (1) "I" (2) "ABC" (3) "-CDE" Cmd> aliases2(b,effect:vector(1,1,0,0,0)) # aliases of AB (1) "AB" (2) "C" (3) "-ABCDE" (4) "-DE" See also aliases3(), confound2(), choosedef2() and choosegen2().

Gary Oehlert 2003-01-15