# float sum( x ) vector x, what is vector x at this position telling?

Discussion in 'C' started by cimon, May 1, 2008.

1. ### cimonNew Member

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I dont understand what is the effect of writing "vector v" with the function . As below

Code:
`print_vector( v ) vector v;`
or

Code:
`float sum( x ) vector x;`
For a function defination , I have only seen and used the normal procedure

like
return_type function_name(input parameters_type input_parameter)

what is the purpose of this extra thing given after this normal syntax.
And sometimes 2 things are given not just one " vector x, y"

Code:
```float scalar_mult( x, y ) vector x, y;
{
int i;
float s = 0.0;
for ( i = 0 ; i < NUM ; i++ )  s += ( x.p[i] * y.p[i] );
return s;
}```
The actual code is below

Code:
```#include <stdio.h>

#define NUM 2         /* Number of input nodes */
#define LIMIT 100     /* Maximum number of inputs the system can handle */
#define SESSIONS 3000 /* Number of training sessions that we'll put the system through */

typedef struct
{
float p[NUM];  //Input vector
} vector;

vector w, test[LIMIT];
int hits[LIMIT], total;

float bias = 0.5;

print_vector( v ) vector v;
{
int i;
for ( i = 0 ; i < NUM ; i++ ) printf("  %.4f ", v.p[i] );
printf("\n");
}

float sum( x ) vector x;
{
int i;
float s = 0.0;
for ( i = 0 ; i < NUM ; i++ )  s += x.p[i];
return s;
}```