EvaluationFactor - GTSAM Docs

Overview¶

EvaluationFactor is a unary factor that enforces a scalar measurement of a basis function at a given point. It is commonly used with pseudo-spectral bases to constrain function values directly.

Authors: Frank Dellaert, et al. (see THANKS for the full author list)

See LICENSE for the license information

# Install GTSAM from pip if running in Google Colab
try:
    import google.colab
    %pip install --quiet gtsam-develop
except ImportError:
    pass  # Not in Colab

Key Functionality / API¶

EvaluationFactor(key, z, model, N, x) constrains $f(x)$ to measurement z.
Optional interval parameters a, b scale the basis domain.

C++ Usage Example¶

auto model = gtsam::noiseModel::Isotropic::Sigma(1, 0.05);
size_t N = 8;
double x = 0.25;
double z = 1.2;
gtsam::EvaluationFactor<gtsam::Chebyshev2> factor(key, z, model, N, x);

Python Usage Example¶

import gtsam

key = gtsam.symbol('c', 0)
model = gtsam.noiseModel.Isotropic.Sigma(1, 0.05)
factor = gtsam.EvaluationFactorChebyshev2(key, 1.2, model, 8, 0.25)
print(factor)

  keys = { c0 }
isotropic dim=1 sigma=0.05
FunctorizedFactor(c0)
  measurement:  1.2
  noise model sigmas: 0.05

Source¶

BasisFactors.h