Classification of AC(Alternating Current) sampling for power network signals was introduced,working principles and error resources in realizing synchronous AC sampling with the use of software were analyzed,conception of period rounding error and variation error and their compensation methods were proposed,and thoughts to keep synchronous when power network was distorting were discussed.

To analyze the rounding error of calculator floating-point numbers arithmetic operation is the foundation of numerical calculation method’s error analysis.

In this paper we analyze the course of rounding error accumulation in the LU decomposition,and create a model,between the loss accuracy of the result and the scale of matrix,to predict the accuracy of large scale LU decompositions.

In this dissertation, we mainly study numerical properties/algorithms and roundoff error estimates related to least squares problems, as mentioned in the following sections:1.

In this paper we analyze the difference between the optimal continuous power vector and the optimal discrete one employing the method of round off error analysis in digital compu.