cannot convert 'dolfin::real' to 'double' for argument '1' to 'double cos(double)

Murtazo Nazarov wrote:
> New question #97399 on DOLFIN:
> https://answers.launchpad.net/dolfin/+question/97399
>
>
> In example in /demo/ode/stiff/cpp/Timedependent1.h I tried to change function f(u,t) into
>
>
> void f(const real* u, real t, real* y)
> {
> y[0] = -1000.0 * u[0] + cos(t);
> }
>
> But I get a compilation error:
>
> In file included from main.cpp:12:
> TestProblem1.h: In member function 'virtual void TestProblem1::f(const dolfin::real*, dolfin::real, dolfin::real*)':
> TestProblem1.h:27: error: cannot convert 'dolfin::real' to 'double' for argument '1' to 'double cos(double)'
> scons: *** [main.o] Error 1
>
> It seems dolfin::real is not double by default for the latest dolfin. Is it bug or I can fix it easily in my code?
> Any suggestion?
>

Use 'double'.

Garth

> Thanks,
> Murtazo
>
>

Garth Wells wrote:
> Question #97399 on DOLFIN changed:
> https://answers.launchpad.net/dolfin/+question/97399
>
> Status: Open => Answered
>
> Garth Wells proposed the following answer:
>
> Murtazo Nazarov wrote:
>
>> New question #97399 on DOLFIN:
>> https://answers.launchpad.net/dolfin/+question/97399
>>
>>
>> In example in /demo/ode/stiff/cpp/Timedependent1.h I tried to change function f(u,t) into
>>
>>
>> void f(const real* u, real t, real* y)
>> {
>> y[0] = -1000.0 * u[0] + cos(t);
>> }
>>
>> But I get a compilation error:
>>
>> In file included from main.cpp:12:
>> TestProblem1.h: In member function 'virtual void TestProblem1::f(const dolfin::real*, dolfin::real, dolfin::real*)':
>> TestProblem1.h:27: error: cannot convert 'dolfin::real' to 'double' for argument '1' to 'double cos(double)'
>> scons: *** [main.o] Error 1
>>
>> It seems dolfin::real is not double by default for the latest dolfin. Is it bug or I can fix it easily in my code?
>> Any suggestion?
>>
>>
>
> Use 'double'.
>
> Garth
>

I tried with 'double'.

  void u0(double* u)
  {
    u[0] = 1.0;
  }

  void f(const double* u, double t, double* y)
  {
    y[0] = -1000.0 * u[0] + cos(t);
  }

Then I got similar error

main.cpp:64: error: cannot declare variable 'test_problem' to be of
abstract type 'TestProblem1'
TestProblem1.h:12: note: because the following virtual functions are
pure within 'TestProblem1':
/afs/nada.kth.se/home/x/u18gh7kx/data/Work/fenics/build/include/dolfin/ode/ODE.h:83:
note: virtual void dolfin::ODE::u0(dolfin::real*)

The I tried like this:

  void u0(real* u)
  {
    u[0] = 1.0;
  }

  void f(const real* u, double t, double* y)
  {
    y[0] = -1000.0 * u[0] + cos(t);
  }

Still error:

In file included from main.cpp:12:
TestProblem1.h: In member function 'void TestProblem1::f(const
dolfin::real*, double, double*)':
TestProblem1.h:27: error: cannot convert '__gmp_expr<__mpf_struct [1],
__gmp_binary_expr<__gmp_expr<__mpf_struct [1], __gmp_binary_expr<double,
__gmp_expr<__mpf_struct [1], __mpf_struct [1]>, __gmp_binary_multiplies>
 >, double, __gmp_binary_plus> >' to 'double' in assignment
scons: *** [main.o] Error 1

>
>> Thanks,
>> Murtazo
>>
>>
>>
>
>

Thanks Anders Logg, that solved my question.