MATLAB Application Program Interface Reference | Help Desk |
Passing Pointers in Fortran
The MATLAB API works with a unique data type, themxArray
. Because there is no way to create a new data type in Fortran 77, MATLAB passes a special identifier, called a pointer, to a Fortran program. You can get information about an mxArray
by passing this pointer to various API functions (called "Access Routines"). These access routines allow you to get a native Fortran data type containing exactly the information you want -- the size of the mxArray
, whether or not it is a string, or its data contents.
There are several implications when using pointers in Fortran:
%VAL
construct.
%VAL
construct, then there is one type of pointer you can use without requiring an access routine, namely a pointer to data (i.e., the pointer returned by mxGetPr
or mxGetPi
). You can use %VAL
to pass this pointer's contents to a subroutine, where it is declared as a Fortran double-precision array.
%VAL
construct, you must use the mxCopy__
routines (e.g., mxCopyPtrToReal8
) to access the contents of the pointer.
integer*8
. On all other platforms, pointers should be declared as integer*4
.
.F
in the examples
directory for a possible approach.