scilab接口程序例程

scilab接口程序例程
下面一步一步的解释几个C语言的例子，理解了这个例子，可以帮助你写出其他的接口函数，并添加到你的工具箱。
例子a:
假定一个程序vectsum，它返回输入的两个向量的和。它的C语言函数名是sci_sumab，在Scilab中调用它的命令是sumab。
为了方便，Scilab中的调用命令都用"sci_"开头。
下面描述了C语言函数vectsum和sci_sumab，这两个函数当我们在Scilab窗口中输入--> Y=sumab(A,B )的时候被使用。

vectsum.c
void vectsum(int n, double * a, double * b, double * y)
{
int k;
for (k = 0; k < n; ++k)
y[k] = a[k] + b[k];
}
sci_sumab.c

#include "stack-c.h"
extern int vectsum(int n, double * a, double * b, double * y);

void sci_sumab(char *fname){
int l1, m1, n1, l2, m2, n2, l3, n;

/* 1 - Check the number of inputs/outputs arguments */
int minlhs=1, maxlhs=1, minrhs=2, maxrhs=2;
CheckRhs(minrhs,maxrhs) ;
CheckLhs(minlhs,maxlhs) ;

/* 2 - Check inputs arguments type, and get the size and the address
in the Scilab stack of the inputs arguments */
GetRhsVar(1, "d", &m1, &n1, &l1);
GetRhsVar(2, "d", &m2, &n2, &l2);

/* 3 - Check that the inputs arguments have the same size */
/* it's possible to use the chekdims and getscalar functions to make these checks*/
n=m2*n2;
if( n1!=n2 || m1!=m2)
{
cerro("inputs arguments must have the same size");
return 0;
}
if(n1!=0 && m1!=0)
if(n1!=1 && m1!=1)
{
cerro("inputs arguments must be vectors");
return(0);
}


/* 4 - Create a new variable corresponding to the output argument */
CreateVar(3,"d",&m2,&n2,&l3);

/* 5 -call vectsum routine: returns in stk(l3) the sum of a and b*/
vectsum(n,stk(l1),stk(l2),stk(l3));

/* 6 - Specif ouput argument */
LhsVar(1) = 3;
return 0;
}
第一步: call CheckRhsVar(minrhs,maxrhs) and CheckLhsVar(minlhs,maxlhs) instructions

CheckRhsVar function uses the arguments minrhs and maxrhs to check that: minrhs <= number of input arguments <= maxrhs The number of inputs and outputs arguments (respectively 2 and 1) of vectsum are constant, so minrhs=maxrhs=2 and minlhs=maxlhs=1, but for certains functions (see example2) they can be variable, in this case the variables minrhs/minlhs and maxrhs/maxlhs are different.
We can use directly the defined variables Rhs(=number of inputs) and Lhs(=number of outputs) instead of the functions CheckRhsVar and CheckLhsVar.

第二步: call GetRhsVar(1,"d",&m1,&n1,&l1) instruction
GetRhsVar function checks that the type of inputs arguments of sumab are correct, and gets their size and their address in the Scilab stack.

We describe below all arguments of GetRhsVar function:

1 : corresponds to the position on the stack of the first input argument of sumab, i.e A, (2 corresponds to B,...)
m1 : gets the rows number of A (m2 for B)
n1 : gets the columns number of A (n2 for B)
l1 : gets the address of A in the Scilab stack (l2 for B)

第三步: call CreateVar(3,"d",&m2,&n2,&l3) instruction

CreateVar function creates in the Stack at the 3th position a variable which corresponds to the output argument of vectsum (here Y)


3 : position of the created variable in the stack. This position (here 3) must follows the position of the last input argument (here2) of sumab
"d": sets the type of the created variable, here double
m2: sets the rows number of the created variable(here equal to the rows number of the second input argument B: m2)
n2: sets the columns number of the first created variable (here equal to the columns number of the second input argument B: n2)
l3: gets the address of the created variable in the Scilab stack

第四步: call vectsum(n,stk(l1),stk(l2),stk(l3)) instruction
The C function vectsum returns in stk(l3) the sum of stk(l1) and stk(l2) (i.e a and b)


第六步: call LhsVar(1) = 3 instruction
The first output argument (here Y) of sumab takes the value of the variable placed in the 3th position on the stack (i.e stk(l3))

例子b:
In the second example we describe the interface program named sci_fun of the Scilab primitive named fun.
This function call the C routines fun1 and fun2 and has 2 syntaxes which are:

First syntax:
--> [X, Y ]=fun(A);
Given a vector A, this function returns the positives components of A in a vector X and the sum of its positives components in a scalar Y.

Second syntax:
--> [X ]=fun(A);
Given a vector A, this function returns the positives components of A in a vector X.

The number of outputs arguments (i.e Lhs value) is variable: for the first syntax Lhs=1, for the second syntax Lhs=2. The number of intputs arguments (i.e Rhs value) is constant: Rhs=1 (first and second syntax).
So the interface program must check that: 1<=Lhs<=2 (set minlhs=1, maxlhs=2) and Rhs=1 (set minrhs=maxrhs=1)

fun1.c (the C function fun1 creates the vector X and the scalar Y. It calls the C function fun2 to get the needed size of X in order to allocate the corresponding memory place)

extern void fun2(double *, int, int *);

void fun1(double * a, int na, int * nx, double ** x , double * y){
int i, k1=0;
*y=0;
fun2(a, na, nx);
*x=(double *)malloc((*nx)*sizeof(double));
*y=0;
for(i=0;i if(a[i]>0) {
*(*x+k1)=a[i];
*y += a[i];
k1++;
};
}
fun2.c

void fun2(double * a, int na, int * nx)
{
int i;
*nx=0;
for(i=0;i if (a[i]>0)
(*nx)++;
}
sci_fun.c

#include "stack-c.h"

extern void fun1(double * , int, int *, double **, double *);

int sci_fun(char *fname)
{
int la, ma, na, m=1, nx, i, lx, ls;
double * x, s;

/* 1 - Check the number of inputs and outputs arguments */
/* You can use the variables: Lhs and Rhs */
int minlhs=1, maxlhs=2, minrhs=1, maxrhs=1;
CheckRhs(minrhs,maxrhs) ;
CheckLhs(minlhs,maxlhs) ;

/* 2 - Check the rhs type, get the rows number (ma) and the columns number (na) of rhs,
and its address (la) in the Scilab stack (first position) */
GetRhsVar(1, "d", &ma, &na, &la);

/* 3 - Check rhs is a vector */
if(ma!=0 && na!=0 )
{
if(ma!=1 && na!=1)
{
cerro("input argument must be a vector");
return(0);
}
}

fun1(stk(la), na*ma, &nx, &x, &s);

/* 4 - Create the place for the first output argument x ( a vector of doubles, size: 1*nx )
to the address lx in the Scilab stack (second position) */
CreateVar(2, "d", &m, &nx, &lx);

/* if there are two outputs variables then: Create the place for the second output
s ( a double, size 1*1) to the address ls in the Scilab stack (third position) */
/* get the value of s, and put it in the Scilab stack */
if(Lhs==2)
{
CreateVar(3, "d", &m, &m, &ls);
*stk(ls)=s;
}

/* get the components of x, and put them in the Scilab stack */
for(i=0;i < nx ; i++)
stk(lx)[i]=x[i];

/* free memory */
free(x);

/* 5 - Specification of outputs variables */
LhsVar(1) = 2;
if(Lhs==2)
LhsVar(2) = 3;
return 0;
}