Error: received a fatal signal (Segmentation fault).
 

Hi, I am trying to read the pressure values at given times by interpolating the table values [t, p] (t - time, p - pressure) in order to obtain transient pressure outlet boundary condition. Thus far the simplest varsion of the code I have looks like this:

#include "udf.h"

int NPts = 58;


float *time_vec, *pressure_vec;



float get_pressure_from_t(float xdata)
{
int i = 0;
int j = 0;
float xL, xU, ydata;

for (i = 1; i<NPts; i++)
{
xL = time_vec[i];
xU = time_vec[i + 1];
if ((xdata >= xL) && (xdata <= xU))
{
ydata = pressure_vec[i] + (xdata - xL) / (xU - xL)*(pressure_vec[i + 1] - pressure_vec[i]);
break;
}
}


if (xdata>time_vec[NPts])
{
ydata = pressure_vec[NPts];
}
if (xdata<time_vec[1])
{
ydata = pressure_vec[1];
}

return ydata;
}


DEFINE_ON_DEMAND(read_pressure)
{

int i;
time_vec = (float *)malloc(NPts*sizeof(float));
pressure_vec = (float *)malloc(NPts*sizeof(float));

for (i = 1; i <= NPts; i++)
{

time_vec[i] = 1.98E-006*(i - 1);

}


pressure_vec[1] = -5253.4;
pressure_vec[2] = -2740.3;
pressure_vec[3] = -402;
pressure_vec[4] = 2705;
pressure_vec[5] = 4537;
pressure_vec[6] = 1905;
pressure_vec[7] = -404;
pressure_vec[8] = -153;
pressure_vec[9] = -2143.1;
pressure_vec[10] = -5998;
pressure_vec[11] = -9295.9;
pressure_vec[12] = -9365.5;
pressure_vec[13] = -6801.4;
pressure_vec[14] = -2888.3;
pressure_vec[15] = 1368;
pressure_vec[16] = 6109;
pressure_vec[17] = 3837;
pressure_vec[18] = -1478.2;
pressure_vec[19] = -6015.7;
pressure_vec[20] = -6496.4;
pressure_vec[21] = -5330;
pressure_vec[22] = -4987.1;
pressure_vec[23] = -5866.3;
pressure_vec[24] = -6786.2;
pressure_vec[25] = -6522.5;
pressure_vec[26] = -5002.9;
pressure_vec[27] = -3634.3;
pressure_vec[28] = -2718.7;
pressure_vec[29] = -2205.4;
pressure_vec[30] = -3768.6;
pressure_vec[31] = -6193.9;
pressure_vec[32] = -7412.6;
pressure_vec[33] = -6739.2;
pressure_vec[34] = -4902.5;
pressure_vec[35] = -1789.4;
pressure_vec[36] = -380;
pressure_vec[37] = 269;
pressure_vec[38] = -30;
pressure_vec[39] = -960;
pressure_vec[40] = -1321;
pressure_vec[41] = -926;
pressure_vec[42] = -901;
pressure_vec[43] = -1395.1;
pressure_vec[44] = -1092;
pressure_vec[45] = 1085;
pressure_vec[46] = 3828;
pressure_vec[47] = 5608;
pressure_vec[48] = 6157;
pressure_vec[49] = 3446;
pressure_vec[50] = 230;
pressure_vec[51] = -2499.2;
pressure_vec[52] = -4046.2;
pressure_vec[53] = -3982;
pressure_vec[54] = -3855;
pressure_vec[55] = -3413.4;
pressure_vec[56] = -2941.6;
pressure_vec[57] = -1750.1;
pressure_vec[58] = 2632;



}


DEFINE_PROFILE(unsteady_pressure, thread, position)
{

float t, pressure;
face_t f;

t = RP_Get_Real("flow-time");

pressure = get_pressure_from_t(t);

begin_f_loop(f, thread)
{
F_PROFILE(f, thread, position) = pressure;
}
end_f_loop(f, thread)

}


Still I get this error: "Error: received a fatal signal (Segmentation fault)." Does anyone have any idea why?

The answer is use execute on demand in menu Define -> User Defined -> Execute on Demand afer compiling and loading the udf. Topic closed.