cspice_vperp

 Abstract I/O Examples Particulars Required Reading Version Index_Entries
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```

#### Abstract

```
CSPICE_VPERP calculates the component of a vector perpendicular to a
second vector.

For important details concerning this module's function, please refer to
the CSPICE routine vperp_c.

```

#### I/O

```
a   a double precision 3-array defining a vector. It is the vector
whose component orthogonal to 'b' is sought.

(There is a unique decomposition of a into a sum v + p, where v is
parallel to b and p is orthogonal to b.  We want the component p.)

b   double precision 3-array. This is the vector used as a reference
for the decomposition of 'a'.

An implicit assumption exists that 'a' and 'b' lie in the same
reference frame. If this is not the case, the numerical result has
no meaning.

the call:

cspice_vperp, a, b, p

returns:

p   a double precision 3-array containing the component of 'a'
orthogonal to 'b'.

```

#### Examples

```
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.

;;
;; Define two vector sets.
;;
a = [ [ 6.D, 6, 6], \$
[ 6,   6, 6], \$
[ 6,   6, 0], \$
[ 6,   0, 0] ]

b = [ [ 2.D, 0, 0], \$
[-3,   0, 0], \$
[ 0,   7, 0], \$
[ 0,   0, 9] ]

;;
;; Calculate the decomposition.
;;
for i=0, 3 do begin
cspice_vperp, a(*,i), b(*,i), p

print, 'a = ', a(*,i)
print, 'b = ', b(*,i)
print, 'p = ', p
print

endfor

IDL outputs:

a =        6.0000000       6.0000000       6.0000000
b =        2.0000000       0.0000000       0.0000000
p =        0.0000000       6.0000000       6.0000000

a =        6.0000000       6.0000000       6.0000000
b =       -3.0000000       0.0000000       0.0000000
p =        0.0000000       6.0000000       6.0000000

a =        6.0000000       6.0000000       0.0000000
b =        0.0000000       7.0000000       0.0000000
p =        6.0000000       0.0000000       0.0000000

a =        6.0000000       0.0000000       0.0000000
b =        0.0000000       0.0000000       9.0000000
p =        6.0000000       0.0000000       0.0000000

```

```
None.

```

```
ICY.REQ

```

#### Version

```
-Icy Version 1.0.2, 22-APR-2010, EDW (JPL)

Edited header, improved/clarified I/O descriptions.

-Icy Version 1.0.1, 09-DEC-2005, EDW (JPL)

Added Examples section.

-Icy Version 1.0.0, 16-JUN-2003, EDW (JPL)

```

#### Index_Entries

```
perpendicular component of a 3-vector

```
`Wed Apr  5 17:58:04 2017`