Mehdi Eshagh - Islamic Azad University, Shahr-e-Rey branch, Tehran, Iran

The first step of designing a geodetic network is Zero order , in which a suitable a suitable datum is defined the problem of datum is a mathematical problem and it refers to projection concepts. In precision point of view, the cofactor matrix of the net point coordinates can be a good means for datum definition. But how can this matrix be used for datum definition? Different function can be defined in this way; one can consider one of the trace, determinant , norm , difference between maximum and minimum latent roots, and maximum latent root of this matrix as a criteria. These criteria can be regarded as scalar risk function . but do the criteria introduce the same datum for a geodetic network? In this paper these criteria are investigated and our numerical results show good agreement among them. Of course this result cannot be a general answer but the maximum latent root, norm, and tract criteria and more suitable for datum definition.

Adjustment , Scalar risk function , constraint , criterion , and datum