Direction and intensity of residual magnetism of rocks measured by Astatic magnetometer, are analyzed with vector analysis method or Fourier series analysis. The former is more popular, however the vector analysis is effective only in the case that curve of residual magnetism is typical sine curve. In another case this method is unsuitable, if the sample has not ideal shape or has magnetic anisotropy. Such samples can be analyzed only approximately by Fourier series expansion. In both cases, it is necessary to measure the curve of residual magnetism as precisely as possible.
The relationship between the results of analysis and precision of the measurement is studied in this paper. The authors also studied the cause of magnetic anisotropy of rock samples whose curve of residual magnetism are not sine curves by microscopic observation. The authors used computers for Fourier series analysis and for the correction of results of residual magnetic declination by a successive approximation.
