straight_line_loan.c


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#include "loans.h"

contract *sl_init(int n, int d, float r, float P) {
	if ((n < 0)) return NULL;
	if ((d > n)||(d < 0)) return NULL;
	contract *c = (contract *)calloc(1, sizeof(contract));
	c->n = (unsigned int)n;
	c->d = (unsigned int)d;
	c->r = r;
	c->P = P;
	c->D = P/(float)n;

	return c;
}

float sl_update(contract *c) {
	if (c->k > c->n)
		return 0.0f;
	c->k++;
	c->I = c->r * c->P;
	c->P = c->P - c->D;
	c->A = c->D + c->I;
	/* c->D is fixed ! */

	return c->A;
}

void sl_free(contract *c) {
	free(c);
}