Me calling Yi Lai, golden gate bridge.

Angxiu Ni (pronounces as "ang sh-you knee")

Tenure-track assistant professor, YMSC, Tsinghua University.
Manager of undergrad affairs, Qiuzhen College, Tsinghua.
Office: Shuangqing Complex B618. You are welcome to chat.
E-mail: niangxiu at tsinghua dot edu dot cn


I will move to a tenure track position at UC Irvine starting fall 2024.
The adjoint shadowing lemma for discrete and contiuous-time hyperbolic systems is accepted at Nonlinearity.
I and Yao Tong extend the equivariant divergence formula to continuous-time.
I developed a 'no-propagate' algorithm; this might the missing piece to overcome non-hyperbolicity.
The theory and algorithm paper on the equivariant divergence formula are accepted at J. Stat. Phys. and SIADS.

Publications and Talks

I differentiate chaos by ergodic theorem formulas and Monte-Carlo algorithms (when dynamics is given, this means to sample by a long orbit). I developed the fastest such formulas and algorithms for the parameter-derivative of long-time-average statistics:
1. Fast tangent response formula, equivariant divergence formula, and algorithms.
2. No-propgate algorithms, which is a long-time variant of the likelihood-ratio trick in random/statistics context.
3. Adjoint theories and algorithms, backpropagation under gradient explosion.
4. Non-intrusive shadowing algorithms.
I am also interested in the numerical interaction with chaos in all fields, such as fluids, geophysics, inference, data assimilation, and machine learning.

Teaching, Spring 2024

Computational probability, YMSC.


Curriculum vitae
I got my PhD from UC Berkeley math and did a postdoc at PKU BICMR.
I have been mentored by John Strain, Pingwen Zhang, Mark Pollicott.
Previous Teaching