Felipe Santibañez-Leal

Felipe Santibañez-Leal

he/him

I&F Decision Science Assoc. Manager @ Accenture | Applied Scientific Researcher

Eight Repos, One Night

1 minute read

Published:

Fixing bugs in 8 repos simultaneously is like being a doctor treating 8 patients with different conditions but the same underlying immune system. They all share the same architectural spine — FastAPI + WebSocket + NumPy — but each one lives in a completely different scientific domain. The haptic simulator speaks in triangles and force vectors. The optical tweezers think in Fourier transforms and phase masks. The well placement optimizer dreams of Darcy flow and permeability fields. And yet, a bug in one teaches you something about all the others.

Tonight was one of those nights. It started with a collision detection bug in the Cellular Potts Model — the contour extent was being compared against the base_radius when it should have been compared against the actual cell boundary. A subtle difference that only shows up when cells elongate during division. Speaking of division, Hertwig’s rule for choosing the division axis had a sign error that made cells divide perpendicular to their longest axis instead of along it. Biology reversed.

Cell model with Gaussian filopodia

Hamiltonian energy:
H = λA(A − Atarget)² + λP(P − Ptarget)²
λA = 0.1, λP = 0.05

The contour extent bug reminded me of the octree bounding box logic in the haptic simulator — same class of error, different geometry. You define a spatial boundary, but when the object deforms or moves, the boundary does not update correctly. In the CPM it was a growing cell; in the haptic sim it was a stylus moving near the edge of a subdivided region. Same mistake, different universe.

And then, while fixing a numerical stability issue in the optical tweezers intensity normalization, I realized the Darcy solver in the well placement code had a nearly identical problem — dividing by a sum that could be zero when all weights collapsed. Two domains, two solvers, one floating-point trap.

The shared patterns make it possible to carry fixes across. The different domains make it interesting. Eight repos, one night, and a lot of coffee.

You May Also Enjoy

Week in review: From developer portfolios to executive narratives

2 minute read

Published:

This week’s biggest change wasn’t technical – it was narrative. I restructured six industry portfolio entries to lead with business impact instead of algorithms. The shift reflects a real career evolution: from implementing models to owning their business outcomes.

Week in review: Vectorization, numerical stability, and biological accuracy

3 minute read

Published:

Modernizing eight research codebases at once sounds like a terrible idea, and some weeks it feels like one. But working across optics, biophysics, robotics, and geostatistics in parallel has surfaced a pattern: the same three engineering challenges keep showing up in every domain, wearing different clothes.

The first SOFI implementation in Chile, modernized

2 minute read

Published:

In 2012, I started working on Super-resolution Optical Fluctuation Imaging at SCIAN-Lab, Universidad de Chile, collaborating remotely with researchers at the III Physics Institute of the University of Gottingen in Germany. Working across continents and time zones with the Gottingen team was both challenging and exhilarating – SOFI was a relatively new technique at the time, and there was limited local expertise in Chile to draw on. Every implementation decision, from the cumulant computation pipeline to the deconvolution strategy, required careful coordination through emails and video calls, often debugging numerical issues with a six-hour time difference. The goal was to implement SOFI from the ground up – cumulant computation, synthetic quantum dot simulators, deconvolution – and apply it to biological samples. After months of work, we achieved the first successful SOFI super-resolution imaging in Chile, resolving structures below the diffraction limit using nothing more than temporal statistics from blinking fluorescent emitters. The pride of being the first group in Chile to produce these results was immense – it proved that cutting-edge computational optics could be done here, not just in European labs with larger budgets and established traditions in the field. That work contributed to a publication at SPIE Photonics West, presenting the cumulant-based framework and validation results.