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mtxvg_c

Table of contents
 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

```   mtxvg_c ( Matrix transpose times vector, general dimension )

void mtxvg_c ( const void   * m1,
const void   * v2,
SpiceInt       nc1,
SpiceInt       nr1r2,
void         * vout   )

```

#### Abstract

```   Multiply the transpose of a matrix and a vector of arbitrary size.
```

#### Required_Reading

```   None.
```

#### Keywords

```   MATRIX
VECTOR

```

#### Brief_I/O

```   VARIABLE  I/O  DESCRIPTION
--------  ---  --------------------------------------------------
m1         I   Left-hand matrix to be multiplied.
v2         I   Right-hand vector to be multiplied.
nc1        I   Column dimension of `m1' and length of `vout'.
nr1r2      I   Row dimension of `m1' and length of `v2'.
vout       O   Product vector `m1' transpose times `v2'.
```

#### Detailed_Input

```   m1          is a double precision matrix of arbitrary size which
forms the left-hand matrix of the multiplication.

v2          is a double precision vector on the right of the
multiplication.

nc1         is the column dimension of `m1' and length of `vout'.

nr1r2       is the row dimension of `m1' and length of `v2'.
```

#### Detailed_Output

```   vout        is the double precision vector which results from
the multiplication

t
vout = (m1)  x  v2

where the superscript `t' denotes the transpose of a matrix.
`vout' has length `nc1'.

`vout' may overwrite `m1' or `v2'.
```

#### Parameters

```   None.
```

#### Exceptions

```   1)  If memory cannot be allocated to create the temporary matrix
required for the execution of the routine, the error
SPICE(MALLOCFAILED) is signaled.
```

#### Files

```   None.
```

#### Particulars

```   The code reflects precisely the following mathematical expression

For each value of the subscript `i' from 1 to `nc1',

vout(i) = Summation from k=1 to nr1r2 of  ( m1(k,i) * v2(k) )
```

#### Examples

```   The 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 matrix and a 3-vector, multiply the transpose of
the matrix by the vector.

Example code begins here.

/.
Program mtxvg_ex1
./
#include <stdio.h>
#include "SpiceUsr.h"

int main( )
{

/.
Local variables.
./
SpiceDouble          vout   [2];

/.
Define `m' and `vin'.
./
SpiceDouble          m      [3][2] = { { 1.0,  2.0 },
{ 1.0,  3.0 },
{ 1.0,  4.0 } };

SpiceDouble          vin    [3] = { 1.0, 2.0, 3.0 };

/.
Multiply the transpose of `m' by `vin'.
./
mtxvg_c ( m, vin, 2, 3, vout );

printf( "Transpose of M times VIN:\n" );
printf( "%10.3f %9.3f\n", vout[0], vout[1] );

return ( 0 );
}

When this program was executed on a Mac/Intel/cc/64-bit
platform, the output was:

Transpose of M times VIN:
6.000    20.000
```

#### Restrictions

```   1)  The user is responsible for checking the magnitudes of the
elements of `m1' and `v2' so that a floating point overflow does
not occur.
```

#### Literature_References

```   None.
```

#### Author_and_Institution

```   N.J. Bachman        (JPL)
J. Diaz del Rio     (ODC Space)
```

#### Version

```   -CSPICE Version 1.3.0, 06-AUG-2021 (JDR)

Changed the input argument name "ncol1" "nc1" 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.

-CSPICE Version 1.2.0, 28-AUG-2001 (NJB)

Const-qualified input arrays.

-CSPICE Version 1.1.0, 08-FEB-1998 (NJB)

Corrected a comment describing the local macro INDEX. Made
miscellaneous code format corrections.

Based on SPICELIB Version 1.0.1, 10-MAR-1992 (WLT)
```

#### Index_Entries

```   matrix transpose times n-dimensional vector
```
`Fri Dec 31 18:41:09 2021`