mxmg_c |

Table of contents## Proceduremxmg_c ( Matrix times matrix, general dimension ) void mxmg_c ( const void * m1, const void * m2, SpiceInt nr1, SpiceInt nc1r2, SpiceInt nc2, void * mout ) ## AbstractMultiply two double precision matrices of arbitrary size. ## Required_ReadingNone. ## KeywordsMATRIX ## Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- m1 I nr1 x nc1r2 double precision matrix. m2 I nc1r2 x nc2 double precision matrix. nr1 I Row dimension of `m1' (and also `mout'). nc1r2 I Column dimension of `m1' and row dimension of `m2'. nc2 I Column dimension of `m2' (and also `mout'). mout O nr1 x nc2 double precision matrix. ## Detailed_Inputm1 is any double precision matrix of arbitrary size. m2 is any double precision matrix of arbitrary size. The number of rows in m2 must match the number of columns in m1. nr1 is the number of rows in both `m1' and `mout'. nc1r2 is the number of columns in `m1' and (by necessity) the number of rows of `m2'. nc2 is the number of columns in both `m2' and `mout'. ## Detailed_Outputmout is the product matrix defined by mout = (m1) x (m2) `mout' is a double precision matrix of dimension nr1 x nc2. `mout' may overwrite `m1' or `m2'. ## ParametersNone. ## Exceptions1) If nc1r2 < 0, the elements of the matrix `mout' are set equal to zero. 2) If memory cannot be allocated to create the temporary matrix required for the execution of the routine, the error SPICE(MALLOCFAILED) is signaled. ## FilesNone. ## ParticularsThe code reflects precisely the following mathematical expression For each value of the subscript `i' from 1 to `nr1', and `j' from 1 to `nc2': mout(i,j) = Summation from k=1 to nc1r2 of m1(i,k) * m2(k,j) ## ExamplesThe numerical results shown for this example may differ across platforms. The results depend on the SPICE kernels used as input, the compiler and supporting libraries, and the machine specific arithmetic implementation. 1) Given a 3x2 and a 2x3 matrices, multiply the first matrix by the second one. Example code begins here. /. Program mxmg_ex1 ./ #include <stdio.h> #include "SpiceUsr.h" int main( ) { /. Local variables. ./ SpiceDouble mout [3][3]; SpiceInt i; /. Define `m1' and `m2'. ./ SpiceDouble m1 [3][2] = { { 1.0, 4.0 }, { 2.0, 5.0 }, { 3.0, 6.0 } }; SpiceDouble m2 [2][3] = { { 1.0, 3.0, 5.0 }, { 2.0, 4.0, 6.0 } }; /. Multiply `m1' by `m2'. ./ ## Restrictions1) No error checking is performed to prevent numeric overflow or underflow. 2) No error checking performed to determine if the input and output matrices have, in fact, been correctly dimensioned. ## Literature_ReferencesNone. ## Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) E.D. Wright (JPL) ## Version-CSPICE Version 1.2.0, 10-AUG-2021 (JDR) Changed the input argument names "nrow1", "ncol1" and "ncol2" to "nr1", "nc1r2" and "nc2" for consistency with other routines. Updated short error message for consistency within CSPICE wrapper interface: MEMALLOCFAILED -> MALLOCFAILED. Edited the header to comply with NAIF standard. Added complete code example based on the existing example. Added entry #1 to -Exceptions section. -CSPICE Version 1.1.2, 16-JAN-2008 (EDW) Corrected typos in header titles: Detailed Input to -Detailed_Input Detailed Output to -Detailed_Output -CSPICE Version 1.1.1, 10-NOV-2006 (EDW) Added -Parameters section header. -CSPICE Version 1.1.0, 28-AUG-2001 (NJB) Const-qualified input arrays. -CSPICE Version 1.0.0, 16-APR-1999 (NJB) ## Index_Entriesmatrix times matrix n-dimensional_case |

Fri Dec 31 18:41:09 2021