IgANet
IgANets - Isogeometric Analysis Networks
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IgANets - Isogeometric Analysis Networks

These pages were created on 04/07/2025 at 18:39:20. The latest revision of this manual is available online.

IgANets (Isogeometric Analysis Networks) is a C++ library that combines Isogeometric Analysis with deep operator learning. It builds upon the C++ API of the Torch library and is written in C++20. The library aims to provide an easy to use, user-friendly and yet computationally efficient framework for implementing IgANet applications.

The library is licenced under the Mozilla Public License Version 2.0.

Getting started

  1. Hello IgANets
  2. Working with B-spline functions

Documentation

Mathematical notation

IgANets adopts the following mathematical symbols and notation conventions.

B-Spline basis functions

  • \( \xi_d \) is the value of the parametric coordinate in the \( d \)-th parametric dimension
  • \( \boldsymbol{\xi} = \left( \xi_1, \dots, \xi_{d_\text{par}} \right)^\top \) is the vector of parametric coordinates in all parametric dimension
  • \( B_{i_d,p_d}(\xi_d) \) is the \( i_d \)-th univariate B-spline basis function in the \( d \)-th parametric dimension evaluated at \( \xi_d \)
  • \( B_I(\boldsymbol{\xi}) = \bigotimes_{d=1}^{d_\text{par}} B_{i_d,p_d}(\xi_d) \) is the \( I \)-th multivariate B-spline basis function
  • \( d_\text{geo} \) is the total number of geometric dimension
  • \( d_\text{par} \) is the total number of parametric dimension
  • \( i_d \) is local index refering to the \( d \)-th dimension
  • \( \mathbf{i} = \left(i_1, \dots, i_d \right) \) is a local multi-index
  • \( I \) is a global index
  • \( n_d \) is the number of univariate B-spline basis functions in the \( d \)-th dimension
  • \( N = n_1\cdot \dots \cdot n_{d_\text{par}} \) is the total number of multivariable B-splines basis functions

B-Spline function spaces

  • \( S^{p}_{\boldsymbol{\alpha}} = \text{span} \left\{ B_{i,p} \right\}_{i=1}^n \) is the function space that is spanned by a univariate B-spline basis of degree \( p \) and regularity vector \( \boldsymbol{\alpha} = \left(\alpha_1, \dots, \alpha_n\right) \). By default, we assume maximal regularity, i.e. \( \alpha_i = p-1 \) for all \( i = 1, \dots, n \)
  • \( S^{p_1,\dots,p_{d_\text{par}}}_{\boldsymbol{\alpha}_1,\dots,\boldsymbol{\alpha}_{d_\text{par}}} \) is the function space that is spanned by a multivariate B-spline basis of degree \( \mathbf{p} = \left(p_1, \dots, p_{d_\text{par}}\right) \) with regularity vectors \( \boldsymbol{\alpha}_d \) for each parametric dimension \( d = 1, \dots d_\text{par} \). By default, we assume maximal regularity (see above)

Copyright

Copyright (c) 2021-2025 Matthias Möller (m.mol.nosp@m.ler@.nosp@m.tudel.nosp@m.ft.n.nosp@m.l).