Hello,
I am trying to differentiate and then evaluate a function with abs(). As a
simple example, consider the function to be f(x) = abs(x). I use the
following code to first define the symbolic function and then try to
evaluate its derivative:
double x = -2;
Differentiation::SD::Expression x_sd("x");
const Differentiation::SD::types::substitution_map substitution_map =
Differentiation::SD::make_substitution_map(
std::pair<Differentiation::SD::Expression, double>{x_sd, x});
std::cout << "Evaluate f(x) at x = " << x << std::endl;
Differentiation::SD::Expression f = abs(x_sd);
std::cout << "Function f(x)= " << f << std::endl;
const double computed_f =
f.substitute_and_evaluate<double>(substitution_map);
std::cout << "Computed Function f(x)= " << computed_f << std::endl;
Differentiation::SD::Expression df_dx_sd = f.differentiate(x_sd);
std::cout << "Derivative of f: " << df_dx_sd << std::endl;
const double computed_df_dx =
df_dx_sd.substitute_and_evaluate<double>(substitution_map);
std::cout << "Computed df_dx: " << computed_df_dx << std::endl;
However, I get the output as below with an error:
[ 91%] Built target main
[100%] Run main with Debug configuration
Evaluate f(x) at x = -2
Function f(x)= abs(x)
Computed Function f(x)= 2
Derivative of f: Derivative(abs(x), x)
terminate called after throwing an instance of
'SymEngine::NotImplementedError'
what(): Not Implemented
make[3]: *** [CMakeFiles/run.dir/build.make:71: CMakeFiles/run] Aborted
(core dumped)
make[2]: *** [CMakeFiles/Makefile2:116: CMakeFiles/run.dir/all] Error 2
make[1]: *** [CMakeFiles/Makefile2:123: CMakeFiles/run.dir/rule] Error 2
make: *** [Makefile:137: run] Error 2
Can someone help me with the issue here?
Thanks
Vinayak
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