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

## Recent

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.

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.

## Misc.

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