-------------------------------------------------------------------------------
module sine_sv_tb (output real sine_val);
    parameter cycles = 5;
    real inc_rad, angle;
    int i, j;

    import "DPI-C" pure function real calc_sine(input real angle);

class rand_sine;
    rand byte steps;
    rand byte amplitude;
    shortreal sine_val;
    real pi = 3.14159265;
    real inc_rad;
    constraint c1 {steps > 15;}
    constraint c2 {amplitude inside{[16:64]};}

    function real calc_rad;
         calc_rad = (2 * pi) / steps;
    endfunction
endclass

    rand_sine rs1 = new;

    initial
    begin
            for (i=0; i<cycles; i++)
            begin
            assert (rs1.randomize()) else $display("Randomize failed");
        $display("Amplitude : %d Steps : %d",rs1.amplitude, rs1.steps);
            inc_rad = rs1.calc_rad;
        $display("Radian increment : %f ",inc_rad);
            angle = 0.0;
                    for(j=0; j<(rs1.steps); j++)
                    begin
                            sine_val = calc_sine(angle) * rs1.amplitude; // call the C
function
                            #5ns angle = angle + inc_rad;
                            $display("Step : %d Sine Value : %f",j,sine_val);
                    end
            end
    $stop();
    end

endmodule

------------ C function --------------------
#include <math.h>
#include <dpiheader.h>

double calc_sine(double angle)
{
        return(sin(angle));
}
------------------------------------------

xsc function1.c function2.c
xelab -svlog ../sim_1/new/dpi_tst.sv -sv_root abc -sv_lib dpi -R -debug typical
xsim work.m

xsc function1.c function2.c