Hi, I am getting infinite recursion (and crash) with the following code, latest eigen from mercurial, using g++4.6 (with -std=c++0x):

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// typedef Eigen::Matrix<double,3,3> Matrix3r;
// Matrix3r Matrix3r T, D; double e;
// double CC(int i);

Real Tnorm=T.norm(), Dnorm=D.norm();
Matrix3r D0=D/Dnorm, T0=T/Tnorm;
Matrix3r R=D0.trace()*Matrix3r::Identity()+CC(1)*exp(CC(2)*D0);
Matrix3r R0=R/R.norm();
Real ec=(1+ec0)*exp(pow(Tnorm,1-CC(3))/(CC(4)*(1-CC(3))))-1;
Real f=CC(4)*D0.trace()+CC(5)*(e-ec)+CC(6);
Real g=-CC(6);
Real h=pow(Tnorm,CC(3));


If I run in gdb, this is bt snip (I stopped the output, it is all the same):

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#81724 0x00007fffe242f639 in Eigen::internal::exp_retval<Eigen::internal::global_math_functions_filtering_base<Eigen::CwiseUnaryOp<Eigen::internal::scalar_multiple_op<double>, Eigen::Matrix<double, 3, 3, 0, 3, 3> const>, void>::type>::type Eigen::internal::exp<Eigen::CwiseUnaryOp<Eigen::internal::scalar_multiple_op<double>, Eigen::Matrix<double, 3, 3, 0, 3, 3> const> >(Eigen::CwiseUnaryOp<Eigen::internal::scalar_multiple_op<double>, Eigen::Matrix<double, 3, 3, 0, 3, 3> const> const&) () from /usr/local/lib/yade-tr2/plugins/libplugins.so
#81725 0x00007fffe242f639 in Eigen::internal::exp_retval<Eigen::internal::global_math_functions_filtering_base<Eigen::CwiseUnaryOp<Eigen::internal::scalar_multiple_op<double>, Eigen::Matrix<double, 3, 3, 0, 3, 3> const>, void>::type>::type Eigen::internal::exp<Eigen::CwiseUnaryOp<Eigen::internal::scalar_multiple_op<double>, Eigen::Matrix<double, 3, 3, 0, 3, 3> const> >(Eigen::CwiseUnaryOp<Eigen::internal::scalar_multiple_op<double>, Eigen::Matrix<double, 3, 3, 0, 3, 3> const> const&) () from /usr/local/lib/yade-tr2/plugins/libplugins.so


What should I do? I am compiling with -ggdb2, though with EIGEN_NO_DEBUG. Could recompiling with eigen debugging help finding the bug? Or is the cause obvious for someone?

Cheers!

Replying to myself, I found that I accidentally typed

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exp(CC(2)*D0)

instead of

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(CC(2)*D0).exp()

. Strange that the compiler accepted the code.

Wouldn't it be worth to specialize std::exp template to Eigen classes to avoid such mistakes?

Sorry for noise.

v

just to be sure, you want the matrix exponential right? not the exponential of each coefficient...

Anyways that's weird that exp(Matrix) compiles, I'll check that...

ok, I got it. This is bug from our side, not from the std.

Thanks, Gael. Yes, I wanted matrix exponential. Cheers!