**ACTION:**- Decompose an linear fit into its constituent parameters:
zero points, scales, nonperpendicularity and orientation.
**CALL:**`CALL sla_DCMPF (COEFFS,XZ,YZ,XS,YS,PERP,ORIENT)`

**GIVEN:**-

*COEFFS***D(6)**transformation coefficients (see note)

**RETURNED:**-

*XZ***D***x*zero point*YZ***D***y*zero point*XS***D***x*scale*YS***D***y*scale*PERP***D**nonperpendicularity (radians) *ORIENT***D**orientation (radians)

**NOTES:**- 1.
- The model relates two sets of coordinates as follows.
Naming the six elements of COEFFS
*a*,*b*,*c*,*d*,*e*&*f*, the model transforms coordinates into coordinates as follows:

The sla_DCMPF routine decomposes this transformation into four steps:*x*=_{2}*a*+*bx*+_{1}*cy*_{1}

*y*=_{2}*d*+*ex*+_{1}*fy*_{1}- (a)
- Zero points:

- (b)
- Scales:

- (c)
- Nonperpendicularity:

- (d)
- Orientation:

- 2.
- See also sla_FITXY, sla_PXY, sla_INVF, sla_XY2XY.

Starlink User Note 67

P. T. Wallace

12 October 1999

E-mail:ptw@star.rl.ac.uk