In computer vision, the rotation of a point by * &theta * around
the * x * axis is accomplished by multiplying by the matrix:[
D. H. Ballard and C. M. Brown, * Computer Vision*, Prentice-Hall, 1982,
p. 477.]

* lccr
1 0 0 0
0 cos &theta - sin &theta 0
0 sin &theta cos &theta 0
0 0 0 1
*

Many of the coefficients in this matrix are the special values ` 0`,
` 1`, or ` -1`. In order to perform this operation with a
standard matrix multiply subroutine, it would be necessary to:

- Create a matrix containing the 16 values.
- Call the subroutine to multiply by this matrix.

Many of the cycles consumed in the matrix multiply would be wasted
because they would be trivial computations (* e.g.*, multiplying
by ` 1` or adding ` 0`).