for i=0,29 { data_fit1[i] = 2*exp(-.9*i/10) }

double parm[2]
parm[0] = 1
parm[1] = 1.5

attr_praxis(1e-5, .1, 1)

fit_praxis(2, "err_fit1", &parm[0])

printf("Final value a=%g  k=%g\n", parm[0], parm[1])
