Oops, my bad. I copied the wrong declaration from the C++ header. This is the original prototype that I'm attempting to duplicate:
void __cdecl c_lin_coeff_dut(int32_t C_in[], double z[], double theta[],
int32_t C_fpp, int32_t C_int_fpp, int32_t z_fpp, int inverse,
double cc[]...