Mathematical Sciences: Studies of the Statistics of Estimated Rotations

张将继续研究估计旋转矩阵的统计性质。一个重要的应用是确定构造板块过去位置的重建误差(俗称“大陆漂移”)。他分析了单位球面上一点到另一点移动的球面回归模型：乘以一个正交旋转矩阵A，然后加上一个随机误差。对于不同的点，旋转矩阵A保持不变，但误差对称地分布在相应的旋转点周围。对该模型的稳健扩展进行了研究。

Chang will continue studies on the statistical properties of estimated rotation matrices. An important application is the determination of the errors in the reconstructions of the past positions of tectonic plates (known popularly as "continental drift"). He analyzes the spherical regression model for the shift from one point to another on the surface of the unit sphere: multiplication by an orthogonal rotation matrix A is followed by the addition of a random error. For different points the rotation matrix A remains the same but the error is symmetrically distributed around the corresponding rotated point. Robust extensions of this model will be studied.