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Enabling mixed-precision with VerifiCarlo: Sharing CEEC experience

May 27 @ 3:00 pm – 4:00 pm
Digital webinar poster for CEEC. Top right corner: CEEC logo in black capital letters with a small curved “wave” accent above the first E. Large heading on the left: “Webinar” followed by a small laptop icon. Second line, large bold text: “Enabling mixed-precision with VerifiCarlo: Sharing CEEC experience” Beneath the heading is a large dark-blue rectangular panel that contains the event details in white text with small icons: First line, next to a calendar icon: “May 27, 2026” Second line, next to a clock icon: “15:00 – 16:00 CEST” Third line, next to an icon of a small building: “Online” Lower part of the blue panel has two short descriptive sections: “Discover … Verificarlo, An open-source framework for verifying and optimizing numerical accuracy.” “Learn about … Verificarlo’s variable precision backend and that let’s one explore the trade-offs between precision and performance IN neuroimaging pipelines, DFT quantum mechanical modeling, structural simulations, and now CFD.” On the right side of the poster, framed by a thin dark border, is the Verificarlo logo: a large green checkmark leaning to the right, followed immediately by the word “verificarlo” in clean, black lowercase letters. The background is white with thin, subtle horizontal wave lines along the bottom edge, giving a light, technical, modern feel.

Join our own Roman Iakymchuk, Umeå University on behalf of CEEC, and Pablo de Oliveira Castro, Université Paris-Saclay UVSQ, for a 2nd look at VerifiCarlo!

Driven by the increasing need to reduce the energy consumption of computing centers and simulations, scientists have begun revising applications, algorithms, and their underlying working/storage precision not just for performance but also for energy efficiency. The goal is to make computational costs sustainable while adhering to the lagom principle—using precision that is “just right” to balance accuracy with efficiency.

However, before lowering precision, one must ensure that the simulation is numerically correct. Verificarlo is an open-source framework designed to verify and optimize numerical accuracy in complex programs. Built on the LLVM infrastructure, it provides various floating-point backends to simulate the effects of numerical errors and lower precision. By leveraging alternative floating-point models, such as Stochastic Rounding, Verificarlo pinpoints numerical bugs in simulation codes. A probabilistic definition of the number of significant digits allows us to estimate computational accuracy accurately.

Through its variable precision backend, Verificarlo enables one to explore the trade-offs between precision and performance by simulating lower precisions in software. It identifies specific code regions that benefit from reduced floating-point formats without sacrificing numerical correctness. This approach has been successfully applied in high-performance computing (HPC) domains such as neuroimaging pipelines, DFT quantum mechanical modeling, structural simulations, and now CFD.

In this webinar, we will introduce Verificarlo, showcase its backends for numerical bug detection and mixed-precision analysis, and present a success story highlighting the road from analysis of codes with Verificarlo to reliable mixed-precision codes.

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