The `fort` function can be used to call a dynamically linked
program. Consider for example the `daxpy` Fortran routine. It performs
the simple vector operation `y=y+a*x` or, to be more specific,
`y(1)=y(1)+a*x(1), y(1+incy)=y(1+incy)+a*x(1+incx),...
y(1+n*incy)=y(1+n*incy)+a*x(1+n*incx)`
where `y` and `x` are two real vectors.
The calling sequence for `daxpy` is as follows:

subroutine daxpy(n,a,x,incx,y,incy)To call

[y1,y2,y3,...]=fort('daxpy', inputs description, 'out', outputs description)Here

where `xi` is the Scilab variable (real vector or matrix) sent to
`daxpy`,
`pi` is the position number of this variable in the calling
sequence of `daxpy` and `ti` is the type of `xi` in `daxpy`
(`t='i' t='r' t='d'` stands for integer, real or double).

`outputs description` is a set of parameters
`[r1,c1],p1,t1`, `[r2,c2],p2,t2`, `[r3,c3],p3,t3`,..

which describes each output variable. `[ri,ci]` is the
2 x 1 integer vector giving the number of rows and columns of the
ith output variable `yi`. `pi` and `ti` are as for
input variables (they can be omitted if a variable is both input and
output).

We see that the arguments of `fort` divided into four groups.
The first argument `'daxpy'` is the name of the called subroutine.
The argument `'out'` divides the remaining arguments into two
groups. The group of arguments between `'daxpy'` and `'out'`
is the list of input arguments, their positions in the call to `daxpy`,
and their data type. The group of arguments to the right of `'out'`
are the dimensions of the output variables, their positions in the call
to `daxpy`, and their data type.
The possible data types are real, integer, and double precision which
are indicated, respectively, by the strings `'r'`, `'i'`, and
`'d'`.
Here we calculate `y=y+a*x` by a call to `daxpy` (assuming
that the `link` command has been done).
We have six input variables
`x1=n, x2=a, x3=x, x4=incx, x5=y, x6=incy`.
Variables `x1, x4` and `x6` are integers and variables
`x2, x3, x5` are double. There is one output variable `y1=y`
at position `p1=5`. To simplify, we assume here that `x` and
`y` have the same length and we take `incx=incy=1`.

-->a=3; -->x=[1,2,3,4]; -->y=[1,1,1,1]; -->incx=1;incy=1; -->n=size(x,'*'); -->y=fort('daxpy',... n,1,'i',... a,2,'d',... x,3,'d',... incx,4,'i',... y,5,'d',... incy,6,'i',... 'out',... [1,n],5,'d'); y = ! 4. 7. 10. 13. !(Since

The same example with the C function `daxpy` (from CBLAS):

int daxpy(int *n, double *da, double *dx, int *incx, double *dy, int *incy) ...

-->link('daxpy.o','daxpy','C') linking files daxpy.o to create a shared executable Linking daxpy (in fact daxpy) Link done ans = 1. -->y=fort('daxpy',... n,1,'i',... a,2,'d',... x,3,'d',... incx,4,'i',... y,5,'d',... incy,6,'i',... 'out',... [1,n],5,'d'); -->y y = ! 4. 7. 10. 13. !

The routines which are linked to Scilab can also access internal
Scilab variables: see the examples in given in the `examples/links`
directory.