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Trailing-Edge - PDP-10 Archives - decus_20tap2_198111 - decus/20-0026/trace.doc
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SUBROUTINE TRACE

PURPOSE
   COMPUTE CUMULATIVE PERCENTAGE OF EIGENVALUES GREATER THAN
   OR EQUAL TO A CONSTANT SPECIFIED BY THE USER.  THIS SUB-
   ROUTINE NORMALLY OCCURS IN A SEQUENCE OF CALLS TO SUB-
   ROUTINES CORRE, EIGEN, TRACE, LOAD, AND VARMX IN THE PER-
   FORMANCE OF A FACTOR ANALYSIS.

USAGE
   CALL TRACE (M,R,CON,K,D)

DESCRIPTION OF PARAMETERS
   M	 - NUMBER OF VARIABLES. M MUST BE > OR = TO 1
   R	 - INPUT MATRIX (SYMMETRIC AND STORED IN COMPRESSED
	   FORM WITH ONLY UPPER TRIANGLE BY COLUMN IN CORE)
	   CONTAINING EIGENVALUES IN DIAGONAL.	EIGENVALUES ARE
	   ARRANGED IN DESCENDING ORDER.  THE ORDER OF MATRIX R
	   IS M BY M.  ONLY M*(M+1)/2 ELEMENTS ARE IN STORAGE.
	   (STORAGE MODE OF 1)
   CON	 - A CONSTANT USED TO DECIDE HOW MANY EIGENVALUES TO
	   RETAIN.  CUMULATIVE PERCENTAGE OF EIGENVALUES
	   WHICH ARE GREATER THAN OR EQUAL TO THIS VALUE IS
	   CALCULATED.
   K	 - OUTPUT VARIABLE CONTAINING THE NUMBER OF EIGENVALUES
	   GREATER THAN OR EQUAL TO CON.  (K IS THE NUMBER OF
	   FACTORS.)
   D	 - OUTPUT VECTOR OF LENGTH M CONTAINING CUMULATIVE
	   PERCENTAGE OF EIGENVALUES WHICH ARE GREATER THAN
	   OR EQUAL TO CON.
REMARKS
   NONE

SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED
   NONE

METHOD
   EACH EIGENVALUE GREATER THAN OR EQUAL TO CON IS DIVIDED BY M
   AND THE RESULT IS ADDED TO THE PREVIOUS TOTAL TO OBTAIN
   THE CUMULATIVE PERCENTAGE FOR EACH EIGENVALUE.