trace_c

Index Page trace_c
A B C D E F G H I J K L M N O P Q R S T U V W X
Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries
#### Procedure
       SpiceDouble trace_c ( ConstSpiceDouble  matrix[3][3] )
#### Abstract
        Return the trace of a 3x3 matrix.
#### Required_Reading
       None.
#### Keywords
        MATRIX
#### Brief_I/O
        VARIABLE  I/O  DESCRIPTION
        --------  ---  --------------------------------------------------
        matrix     I     3x3 matrix of double precision numbers.
        trace      O     The trace of matrix.
#### Detailed_Input
        matrix  is a double precision 3x3 matrix.
#### Detailed_Output
        trace   is the trace of matrix, i.e. it is the sum of the
                diagonal elements of matrix.
#### Parameters
       None.
#### Exceptions
        Error free.
#### Files
        None
#### Particulars
        trace_c simply executes in C code the following loop:

        trace_c = Summation from i = 1 to 3 of matrix[i][i]

        This functions implements no error detection.
#### Examples
                              | 3   5   7 |
        Suppose that matrix = | 0  -2   8 |  , then
                              | 4   0  -1 |

        trace_c (matrix) = 0.  (which is the sum of 3, -2 and -1).
#### Restrictions
        No checking is performed to guard against floating point overflow
        or underflow.  This routine should probably not be used if the
        input matrix is expected to have large double precision numbers
        along the diagonal.
#### Literature_References
        None
#### Author_and_Institution
        W.L. Taber      (JPL)
        E.D. Wright     (JPL)
#### Version
       -CSPICE Version 1.0.0, 29-JUN-1999
#### Index_Entries
       trace of a 3x3_matrix
#### Link to routine trace_c source file trace_c.c

    Thu Apr 16 08:59:24 2009