What is the fine-grained topic of the following text: Let C be the companion matrix of a monic polynomial p over a field F. We prove that if A is a matrix whose entries are rational functions of Buy Timberland Work Boots Canada the coefficients of p over F and whose characteristic polynomial is p, then A has at least as many nonzero entries as C. The X-ray source is a key part for public security detection applied in airport, custom and many public security detection places. Only return the topic.
Comparison of Nonzero Entries in Matrices and X-ray Source Importance for Public Security Detection