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#! /usr/bin/env ruby
# This is 'curve1.c' demo done with RubyInline gem (instead of using swig)
# Contributed by Igor Drozdov <idrozdov@gmail.com> 2012
# $ ruby curve1_rubyinline.rb
#
# Requirements:
#
# $ gem install RubyInline
#
# To make sure header files and shared librares can be found,
# export appropriate LD_LIBRARY_PATH and C_INCLUDE_PATH.
require 'rubygems'
require 'inline'
class Curve
inline(:C) do |builder|
builder.include("\"lmcurve.h\"")
builder.include("\"lmmin.h\"")
builder.include("<math.h>")
builder.include("<stdio.h>")
builder.include("<ruby.h>)")
builder.add_link_flags("-llmmin")
builder.c_raw <<EOC
double f( double t, const double *p )
{
return p[0] + p[1]*(t-p[2])*(t-p[2]);
}
EOC
builder.c <<EOC
VALUE demo(VALUE t_ary, VALUE y_ary) {
/* parameter vector */
int n_par = 3; // number of parameters in model function f
double par[3] = { 1, 0, -1 }; // relatively bad starting value
/* data pairs: slightly distorted standard parabola */
int m_dat = 11; // number of data pairs
int i;
/* ruby macros dealing with inputs */
int t_len = RARRAY_LEN(t_ary);
int y_len = RARRAY_LEN(y_ary);
double t[t_len];
double y[t_len];
VALUE *t_arr = RARRAY_PTR(t_ary);
VALUE *y_arr = RARRAY_PTR(y_ary);
VALUE result_pars = rb_ary_new(); // ruby array containing fitted params
/* auxiliary parameters */
lm_status_struct status;
lm_control_struct control = lm_control_double;
for (i = 0; i < t_len; i++) {
t[i] = NUM2DBL(t_arr[i]);
y[i] = NUM2DBL(y_arr[i]);
}
lmcurve_fit( n_par, par, m_dat, t, y, f, &control, &status );
/* print results */
printf( "\\nResults:\\n" );
printf( "status after %d function evaluations:\\n %s\\n",
status.nfev, lm_infmsg[status.outcome] );
printf("obtained parameters:\\n");
for ( i = 0; i < n_par; ++i)
rb_ary_push(result_pars,DBL2NUM(par[i]));
printf(" par[%i] = %12g\\n", i, par[i]);
printf("obtained norm:\\n %12g\\n", status.fnorm );
printf("fitting data as follows:\\n");
for ( i = 0; i < m_dat; ++i)
printf( " t[%2d]=%12g y=%12g fit=%12g residue=%12g\\n",
i, t[i], y[i], f(t[i],par), y[i] - f(t[i],par) );
printf("\\n");
return result_pars;
}
EOC
end
end
#
t = [ -5.0, -4.0, -3.0, -2.0, -1.0, 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 ]
y = [ 25.5, 16.6, 9.9, 4.4, 1.1, 0, 1.1, 4.2, 9.3, 16.4, 25.5 ]
c = Curve.new
p c.demo(t,y)