Linear Classifier in C, C (clang)

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//clang 3.7.0
//Linear Classifier in C Copyright(C) 2016 Henry Kroll III www.thenerdshow.com
//usr/local/bin/anch -std=c99 -keep -run "$0" "$@" ; exit
#include <stdio.h>
#include <stdlib.h>
#define RPT(i, n) for (int i=n;i--;)
#define LN 3
double weights[LN] = {0.0, 0.0, 0.0};
int training_set[][6][LN] = {{{1, 0, 0}, {1}}, {{1, 0, 1}, {1}}, {{1, 1, 0}, {1}}, {{1, 1, 1}, {0}}, {{-1}} }; 
//dot product
double dot_product (int *values, double *weights) {
    double sum = 0.0, value, weight;
    RPT (i, LN) {
        value  = (double)values[i], weight = weights[i];
        sum += value * weight;
    } return sum;
} int main (void) {
    double threshold = 0.5;
    double learning_rate = 1.0;
    RPT (iter, 50) {
        RPT (i, 60) putchar ('=') ;putchar ('\n');
        int error_count = 0;
        for (int i=0;training_set[i][0][0]>=0;i++) {
            int *input_vector   = training_set[i][0];
            int *desired_output = training_set[i][1];
            double result = dot_product (input_vector, weights) > threshold;
            double error = (double)*desired_output - result;
            int fail = (int)(abs(error) + threshold);
            printf ("(%i, %i, %i) ", input_vector[0], input_vector[1], input_vector[2]);
            printf ("goal: %i got: %4.2f error: %5.2f %s\n",
            *desired_output, result, error, fail?"fail":"success");
            if (fail) {
                error_count++;
                RPT (index, LN) {
                    int value = input_vector[index];
                    double fact = learning_rate * error * (double)value;
                    weights[index] += fact;
        }   }   } if (error_count == 0) {
            RPT (i, 60) putchar ('=') ;putchar ('\n');
            printf ("Success in %i iterations.", 50-iter);
            break;
    }   } return EXIT_SUCCESS;
}

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Compilation time: 0.12 sec, absolute running time: 0.14 sec, cpu time: 0 sec, memory peak: 3 Mb, absolute service time: 0,34 sec