Instructions do not work with custom floatt

Try this instead:

float x = ALT_CI_TESTE_INST(0.0f);

The 'f' tells the compiler to use a single precision value instead of double precision (default). There is also a flag you can pass to the compiler to tell it to treat all floating point constants as type 'float' instead of 'double' but I forget what to use (I don't recommend it either since you might accidentally break some code that needed to use double precision constants).