Annamalai

Emacs Literate Calc Mode

Tue, 10 Nov 2026 11:00:00 +0530

I just got to know that literate-calc-mode exists, while browsing this week’s Sacha’s Blog. You can use it within org files itself! No need to remember calc shortcuts!.

Updating Git Submodules Recursively

Tue, 10 Nov 2026 11:00:00 +0530

To pull and update all nested submodules in one command:

git submodule update --init --recursive --remote

State Estimation with Kalman Filters

Tue, 10 Nov 2026 10:00:00 +0530

A quick look at the discrete state-space update step.

The linear measurement update equation is given by:

$$x_k = A x_{k-1} + B u_k + w_k$$

Where the Kalman Gain $K_k$ scales the innovation:

$$K_k = P_k^- H^T (H P_k^- H^T + R)^{-1}$$

Inline math check: the error covariance shrinks when $R \to 0$.