For explanations about "leading dimension", see e.g. here: http://www.inf.bv.tum.de/~heisserer/softwarelab04/index.html

"Note that for cblas-functions the leading dimension (for 2D arrays in C-fashion, i.e. row major order) is the number of columns of the matrix (not the rows as in Fortran). The leading dimension is the number of entries in memory that separate the e.g. first elements of rows in c-fashion storage (row major order, i.e. elements of one row are contiguous in memory). As Fortran stores in column major order the leading dimension is the number of rows."