Tutorial

Working with Vectors

Download the source code and compile it - in the case of an installation in the own home directory - e.g. by :

gcc example1.c -O2 -march=athlon-xp -I $HOME/local/include -I $HOME/include/UMFPACK -L $HOME/local/lib $HOME/local/lib/libmeml.a -lm -llapack /usr/lib/libf2c.a -lumfpack -lamd -lcblas -lf77blas -latlas -o example1

/*
   This is a small example how to do
   vector manipulation and vector operations with meml

   more functions are documented under

   http://www.meml.smial.de/doc/group__meml__speichermanagent.html
   http://www.meml.smial.de/doc/group__meml__vector__manipulation.html
   and
   http://www.meml.smial.de/doc/group__meml__vector__vector__operatoren.html
*/

# include "meml.h"
# define SIZE 10000

int main (void)
{
    int i;
    VECTOR *a, *b, *c, *d;

    /* creating a vector of the dimension 10 filled with zeros */
    a = meml_vector_new_zeros(10);
    /* you can do the same by */
    b = meml_vector_new(10);
    /* and now create a vector filled with ones */
    c = meml_vector_new_ones(10);

    /* lets scale the last vector with 42 */
    meml_vector_scaling_f(42,c);

    /* now lets change a single element in a*/

    /* most secure but quite slow via */
    meml_vector_element_set (a, 5, -42);
    /* a bit faster */
    meml_vector_element_set_f (a, 6, -42);
    /* or direct */
    a->data[7] = -42;
    /* this works well with vectors
       do never try this with a matrix because you
       can not be sure how the data is stored */

    /* now add a to c and store the result in d */
    d = meml_vector_add(a,c);
    /* now add a to c and store the result in c */
    meml_vector_add_f(a,c);

    printf("now lets build the scalarproduct of a and c"
           "which is %e \n",
           meml_vector_scalarproduct(a,c));

    printf("The norm of c is : %e \n",meml_vector_norm(c));
    printf("The maximum norm of c is : %e \n",meml_vector_norm_max(c));

    meml_vector_free(a);
    meml_vector_free(b);
    meml_vector_free(c);
    meml_vector_free(d);

    exit(EXIT_SUCCESS);
}

Previous : "Preamble" Next "Example : Working with Matrices"