### trigonometry

#### Counting trig ops as measure() function to fu() in sympy

How do I count the number of trig operations in an expression? I have an expression of the form a*sin(x)+b*cos(x) that I would like sympy to convert to c*sin(x+phi). #asmeurer made a comment in an earlier question about simplifying trig expressions that suggested the fu() algorithm can be tuned to minimize an arbitrary measure. I suspect I can get my expression to reduce if I set measure to be the number of trig ops in the expression.

The following is a way to get the set of functions: >>> from sympy.functions.elementary.trigonometric import TrigonometricFunction >>> eq=a*sin(x)+b*cos(x) >>> len(eq.atoms(TrigonometricFunction)) 2 If you wanted the actual number of times that such functions occurred (counting the same function more than once) you might try a custom function like preorder_traversal from sympy.core.exprtools, registering each time a TrigonometricFunction was encountered.

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