This is because he has exaggerated the land distances between the east and the west, by a factor of approximately 1. 4. Almost the same factor of exaggeration can also be found in the measurement of geographical longitudes made by Ptolemy in the West.

• 该文对里差概念和数值进行了分析，发现耶律楚材的里差数值偏小，原因是他使用的东西距离数值过大，约为实际距离的1.；4倍。