Table of contents
CSPICE_MXM calculates the product of two 3x3 matrices
using the classic definition of matrix multiplication,
returning a 3x3 matrix as output.
Given:
m1 an arbitrary 3x3 double precision matrix.
help, m1
DOUBLE = Array[3,3]
m2 an arbitrary 3x3 double precision matrix.
help, m2
DOUBLE = Array[3,3]
the call:
cspice_mxm, m1, m2, mout
returns:
mout a 3x3 double precision matrix.
help, mout
DOUBLE = Array[3,3]
`mout' is the product m1*m2.
None.
Any numerical results shown for this example may differ between
platforms as the results depend on the SPICE kernels used as input
and the machine specific arithmetic implementation.
1) Given two 3x3 double precision matrices, compute their
product.
Example code begins here.
PRO mxm_ex1
;;
;; Define `m1' and `m2'.
;;
m1 = [ [ 1.D0, 1.D0, 0.D0 ], $
[ -1.D0, 1.D0, 0.D0 ], $
[ 0.D0, 0.D0, 1.D0 ] ]
m2 = [ [ 1.D0, 0.D0, 0.D0 ], $
[ 0.D0, 1.D0, 1.D0 ], $
[ 0.D0, -1.D0, 1.D0 ] ]
;;
;; Compute `m1' times `m2'.
;;
cspice_mxm, m1, m2, mout
print, format='(A)', 'M1:'
print, format='(3F16.7)', m1
print
print, format='(A)', 'M2:'
print, format='(3F16.7)', m2
print
print, format='(A)', 'M1 times M2:'
print, format='(3F16.7)', mout
END
When this program was executed on a Mac/Intel/IDL8.x/64-bit
platform, the output was:
M1:
1.0000000 1.0000000 0.0000000
-1.0000000 1.0000000 0.0000000
0.0000000 0.0000000 1.0000000
M2:
1.0000000 0.0000000 0.0000000
0.0000000 1.0000000 1.0000000
0.0000000 -1.0000000 1.0000000
M1 times M2:
1.0000000 1.0000000 1.0000000
-1.0000000 1.0000000 1.0000000
0.0000000 -1.0000000 1.0000000
The code reflects precisely the following mathematical expression
For each value of the subscripts `i' and `j' from 0 to 2:
2
.-----
\
mout[i,j] = ) m1[i,k] * m2[k,j]
/
'-----
k=0
Native IDL code to calculate the same matrix result:
c = a ## b
1) If any of the input arguments, `m1' or `m2', is undefined, an
error is signaled by the IDL error handling system.
2) If any of the input arguments, `m1' or `m2', is not of the
expected type, or it does not have the expected dimensions and
size, an error is signaled by the Icy interface.
3) If the output argument `mout' is not a named variable, an
error is signaled by the Icy interface.
None.
None.
ICY.REQ
None.
J. Diaz del Rio (ODC Space)
E.D. Wright (JPL)
-Icy Version 1.0.3, 10-AUG-2021 (JDR)
Edited the header to comply with NAIF standard. Added complete
code example based on existing example.
Changed the argument names in order to match those given within the
IDL bridge code.
Added -Parameters, -Exceptions, -Files, -Restrictions,
-Literature_References and -Author_and_Institution sections, and
completed -Particulars section.
Removed reference to the routine's corresponding CSPICE header from
-Abstract section.
Added arguments' type and size information in the -I/O section.
-Icy Version 1.0.2, 13-JUN-2011 (EDW)
Edits to comply with NAIF standard for Icy headers.
-Icy Version 1.0.1, 09-DEC-2005 (EDW)
Added -Examples section.
-Icy Version 1.0.0, 16-JUN-2003 (EDW)
matrix times matrix 3x3_case
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