solved arellano (#32)

* remove np with at in jax; replace random func in jax

* Delete arellano_jax-checkpoint.ipynb

remove 
arellano_jax-checkpoint.ipynb no need

* Delete arellano_jax.ipynb

remove 
arellano_jax.ipynb no need

* change title

* drop down for the exercise, change the title

* add qe on top of the lec

* fix small issues

* correct citation, correct math expression

* change the quant-econ.bib

* Update lectures/arellano.md

made the cell outputs hidden and fixed some minor typos.

Co-authored-by: zhc <[email protected]>

* Update lectures/arellano.md

made the cell outputs hidden and fixed some minor typos.

Co-authored-by: zhc <[email protected]>

* Update lectures/arellano.md

made the cell outputs hidden and fixed some minor typos.

Co-authored-by: zhc <[email protected]>

* Update lectures/arellano.md

made the cell outputs hidden and fixed some minor typos.

Co-authored-by: zhc <[email protected]>

---------

Co-authored-by: zhc <[email protected]>
Co-authored-by: mmcky <[email protected]>

Author: 3 people

lectures/_static/quant-econ.bib

@@ -2496,3 +2496,11 @@ @article{stachurski2019impossibility
   year      = {2019},
   publisher = {Elsevier}
 }
+
+@article{Are08,
+  author  = {Cristina Arellano},
+  journal = {The American Economic Review},
+  pages   = {690--712},
+  title   = {{Default risk and income fluctuations in emerging economies}},
+  year    = {2008}
+}

lectures/_toc.yml

@@ -19,6 +19,7 @@ parts:
   - file: short_path
   - file: opt_invest
   - file: opt_savings
+  - file: arellano
   - file: aiyagari_jax
 - caption: Other
   numbered: true