The TRACE function computes the trace of an n by n array.
This routine is written in the IDL language. Its source code can be found in the file trace.pro in the lib subdirectory of the IDL distribution.
Result = TRACE( A [, /DOUBLE] )
Returns the sum of the values along the array diagonal.
An n by n real or complex array.
Set this keyword to force the computation to be done in double-precision arithmetic.
; Define an array: A = [[ 2.0,1.0, 1.0, 1.5], $ [ 4.0, -6.0, 0.0, 0.0], $ [-2.0, 7.0, 2.0, 2.5], $ [ 1.0, 0.5, 0.0, 5.0]] ; Compute the trace of A: result = TRACE(A) ;Print the result: PRINT, 'TRACE(A) = ', result
IDL prints:
TRACE(A) = 3.00000
Introduced: 5.0