How to Evaluate sympy.core.add.Add in Python at a Given Point

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The Problem

For example, consider the following setup:

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After this, you might try to evaluate g[0](1,1,0) and receive an error saying 'Add' object is not callable. This highlights the issue: the Add object cannot be directly called as a function.

The Solution

Instead of attempting to call the Add object as a function, you can evaluate the expression by substituting values for its symbols. Here’s how you can do that using the subs method:

Step 1: Inspect the Generated Expression

Start by looking at the expression g[0] to understand its structure:

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This would output the expression in a readable format, which consists of the original mathematical function modified according to your derivation.

Step 2: Substitute Values for Variables

You can substitute specific values for each of the variables in the expression to evaluate it at a certain point. Here’s how you can do it:

Substituting for one variable:

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Substituting for two variables:

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Substituting all variables:

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Step 3: Evaluation Result

By the time you reach the last step of substituting all variable values, you will have evaluated the expression correctly.

For instance:

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Conclusion

With these steps, you can confidently evaluate any symbolic expression at any given point!