The name of the Scilab function is c=som(a,b). Its two inputs are row vectors and its output is a column vector.
The corresponding Fortran subroutine is subroutine fsom(a,n,b,m,c). Its arguments are a real array with dimension n (used as input), another real array with dimension m (used as input) and a real array (used as output). These dimensions m and n are determined at the calling of the Scilab function and do not need to appear as Scilab variables.
Intersci will do the job to make the necessary conversions to transform the double precision (default in Scilab) row vector a into a real array and to transform the real array c into a double precision row vector.
The description file is the following:
som a b a row m b row n c column n fsom a n b m c a real n integer b real m integer c real out sequence c ***********************