Parser

[rsiddu0511]

I used "Parser" function to find the value of variables using a set of constants.
But I encountered the following error:

Parser is not a member of amrex

I used the following lines in my GNUMakeFile.

amrex::Parser parser("a=(b*c)/(d*d)");

parser.setConstant(b);
parser.setConstant(c);
parser.setConstant(d);
parser.registerVariables({"a"});
auto f = parser.compile<2>();

Also, the compilation seems to have some issues too:
expected primary-expression before ‘)’ token

[WeiqunZhang]

Parser is not a member of amrex

Is there #include <AMReX_Parser.H>?

I used the following lines in my GNUMakeFile.

I assume this is a typo. Parser is for C++ code, not for make.

amrex::Parser parser("a=(b*c)/(d*d)");

This is not a valid code for the parser. What do you want to compute? (b*c)/(d*d)? Assignment like a=...; can be used to define a local variable that's internal to the parser. But the parser expression must have an expression as the last statement, and that will be its return value when ParserExecutor<N>::operator() is called. a=(b*c)/(d*d); a is valid, but then a is not a variable to be registered with registerVariables. Parser is usually used to evaluate a runtime string. If it's a string literal known at compile time, one should just use a C++ function for it.

parser.setConstant(b);

The function void setConstant (std::string const& name, amrex::Real c); takes two arguments.

parser.registerVariables({"a"});
auto f = parser.compile<2>();