1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
|
/*
The files demo_plugin.c and gnuplot_plugin.h serve as templates
showing how to create an external shared object containing functions
that can be accessed from inside a gnuplot session using the import
command. For example, after compiling this file into a shared
object (gnuplot_plugin.so or gnuplot_plugin.dll) the functions it
contains can be imported as shown:
gnuplot> import divisors(x) from "demo_plugin"
gnuplot> import mysinc(x) from "demo_plugin:sinc"
gnuplot> import nsinc(N,x) from "demo_plugin"
*/
#include "gnuplot_plugin.h"
#include <math.h>
/* This function returns the number of divisors of the first argument */
DLLEXPORT struct value divisors(int nargs, struct value *arg, void *p)
{
int a = IVAL(arg[0]);
int i = 1;
int j = a;
struct value r;
r.type = INTGR;
r.v.int_val = 0;
/* Enforce a match between the number of parameters declared
* by the gnuplot import command and the number implemented here.
*/
RETURN_ERROR_IF_WRONG_NARGS(r, nargs, 1);
/* Sanity check on argument type */
RETURN_ERROR_IF_NONNUMERIC(r, arg[0]);
while (i <= j)
{
if (a == i*j)
{
r.v.int_val += 1 + (i!=j);
}
i++;
j=a/i;
}
return r;
}
DLLEXPORT struct value sinc(int nargs, struct value *arg, void *p)
{
double x = RVAL(arg[0]);
struct value r;
r.type = CMPLX;
/* Enforce a match between the number of parameters declared
* by the gnuplot import command and the number implemented here.
*/
RETURN_ERROR_IF_WRONG_NARGS(r, nargs, 1);
/* Sanity check on argument type */
RETURN_ERROR_IF_NONNUMERIC(r, arg[0]);
r.v.cmplx_val.real = sin(x)/x;
r.v.cmplx_val.imag = 0.0;
return r;
}
DLLEXPORT struct value nsinc(int nargs, struct value *arg, void *p)
{
struct value r;
int n; /* 1st parameter */
double x; /* 2nd parameter */
/* Enforce a match between the number of parameters declared
* by the gnuplot import command and the number implemented here.
*/
RETURN_ERROR_IF_WRONG_NARGS(r, nargs, 2);
/* Sanity check on argument type */
RETURN_ERROR_IF_NONNUMERIC(r, arg[0]);
RETURN_ERROR_IF_NONNUMERIC(r, arg[1]);
n = IVAL(arg[0]);
x = RVAL(arg[1]);
r.type = CMPLX;
r.v.cmplx_val.real = n * sin(x)/x;
r.v.cmplx_val.imag = 0.0;
return r;
}
|
