Custom factor without Jacobian

[shounak873]

Hi, I want to create a custom factor but I am not sure how to get the analytic Jacobian. Can I just create the factor with the error formula z - f(x) and let gtsam calculate the Jacobian numerically?

[yetongumich]

You create a custom function that computes z-f(x). Then, in the evaluateError function of your customized factor, you can call the numericalDerivative function to compute the Jacobian numerically.
Examples in testNumericalDerivative.cpp will help you get familiar with the function.

[goodgoodliving]

You create a custom function that computes z-f(x). Then, in the evaluateError function of your customized factor, you can call the numericalDerivative function to compute the Jacobian numerically. Examples in testNumericalDerivative.cpp will help you get familiar with the function.

@yetongumich
Hello, may I ask if it's possible to automatically solve for the Jacobian using GTSAM if I'm implementing a custom factor in Python, where I only know the error function and am not familiar with how to perform the Jacobian calculation? Are there relevant interfaces for this in GTSAM?