istream constructors try to create zero size gsl vector/matrix.

[Peter]

gsl: init_source.c:29: ERROR: matrix dimension n1 must be positive integer

This should be checked for. Either set gsl vector*/matrix* to null or throw an exception.

[Jari Häkkinen]

This error occurs if there is no stream or if the stream is empty. If the stream is empty then a 0x0 matrix should be created.

[Peter]

in [1147]