Scilab Bag Of Tricks - Claymore

Chapter 4. Unknown Spots
Lisp as a (functional) language which employs pure prefix syntax all functions and operators are
written before all arguments.
(+ 3.9 54.0 -4.5 74.5 -57 -56)
(setq x (list "a" -1 (- 3 10)))
(length x)
The same expressions look more or less differently in Scilab:
3.9 + 54.0 + (-4.5) + 74.5 + (-57) + (-56)
sum( [3.9 54.0 -4.5 74.5 -57 -56] ) – alternative to previous line
x = list("a", -1, (3 - 10))
length(x)
As becomes clear in the above example, operators are specially written functions, but otherwise
behave like ordinary functions.
Overloading has been hyped since to advent of C++. A closer look reveals that even Fortran-77
endows certain intrinsics with an overloaded syntax. What the heck is overloading? To overload a
symbol means assigning another meaning to it, augmenting the existing meaning(s). Typically, the
symbol is a function name and the additional meaning is an additional function definition.
How can the language decide which definition to take? That depends on the language. The most
common scheme to determine which function definition to trigger is the analysis of the actual
function arguments. Fortran-77 provides so-called generic functions, sin is one example, which can
be called with arguments of several types and the compiler selects the routine that matches that type.
program f77ovl
implicit none
real xr, s1
double precision xd, s2
complex xc, s3
* floating point literals default to real*4 in f77
xr = 1.0
s1 = sin(xr) – compiler selects single precision routine
xd = 1.0d0
s2 = sin(xd) – compiler selects double precision routine
xc = (1.0, 0.0)
s3 = sin(xc) – compiler selects complex routine
* alternative using explicit call
s2 = dsin(xd) – user demands double precision routine
s3 = csin(xc) – user demands complex routine
end
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