This program shows how to allocate, initialize and read from a vector
using the functions gsl_vector_alloc
, gsl_vector_set
and
gsl_vector_get
.
#include <stdio.h> #include <gsl/gsl_vector.h> int main (void) { int i; gsl_vector * v = gsl_vector_alloc (3); for (i = 0; i < 3; i++) { gsl_vector_set (v, i, 1.23 + i); } for (i = 0; i < 100; i++) { printf("v_%d = %g\n", i, gsl_vector_get (v, i)); } return 0; }
Here is the output from the program. The final loop attempts to read
outside the range of the vector v
, and the error is trapped by
the range-checking code in gsl_vector_get
.
v_0 = 1.23 v_1 = 2.23 v_2 = 3.23 gsl: vector_source.c:12: ERROR: index out of range IOT trap/Abort (core dumped)
The next program shows how to write a vector to a file.
#include <stdio.h> #include <gsl/gsl_vector.h> int main (void) { int i; gsl_vector * v = gsl_vector_alloc (100); for (i = 0; i < 100; i++) { gsl_vector_set (v, i, 1.23 + i); } { FILE * f = fopen("test.dat", "w"); gsl_vector_fprintf (f, v, "%.5g"); fclose (f); } return 0; }
After running this program the file `test.dat' should contain the
elements of v
, written using the format specifier
%.5g
. The vector could then be read back in using the function
gsl_vector_fscanf (f, v)
.