Hello,
I have a compilation error concerning the operator+.
It seems that this operator for scalars is defined but it does not compile.
I use the eigen library distributed on ubuntu.

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VectorXd x(21);
x <<  -2.0, -1.7, -1.4, -1.1, -0.8 ,-0.5, -0.2 , 0.1 , 0.4 , 0.7 , 1.0 , 1.3 , 1.6 , 1.9 , 2.2, 2.5 , 2.8 , 3.1  ,3.4,  3.7 , 4.0;

VectorXd xx = x+10;


the compile error message :

/home/rtrepos/usr/src/vle_dev/eigen_utils/src/test_eigen_utils.cpp: In function ‘int main(int, const char**)’:
/home/rtrepos/usr/src/vle_dev/eigen_utils/src/test_eigen_utils.cpp:300: error: no match for ‘operator+’ in ‘x + 10’

Best regards.

have a look at the tutorial:
http://eigen.tuxfamily.org/dox/Tutorial ... cOperators

the correct syntax for this operation is:

xx = x .cwise()+ 10;

here you have to add the .cwise() prefix to make it clear you don't want to add 10 to all coefficients in contrast to:

x + 10 I

where I is the identity matrix.

You can't add a number to a vector like that. If you want to add that number to all coeffs of the vector, do:

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v.cwise() + 10.0


Note that "cwise()" is just a "prefix" for the operator+. That's why you write it only on the left hand side, and the result of the operator+ is again just a vector expression.

Sorry, actually I saw it on the tutorial but I forgot it.
Thank you, I'll take more time before posting now..