fourier inverse of complex matrix

[pompo]

i have 2D complex array as follow
MatComplex_IO X (512,512)

i wanna to get the fourier inverse of it ?

[pompo]

i get the real part of the array - UR - and try to get the inverse fourier for it
it's also 512 * 512

MatDoub_IO UR (512,512)
Doub *dr=&UR[0][0];
Int p[2];
p[0]=UR.nrows();
p[1]=UR.ncols();
VecInt_I a(2,p);
fourn(dr,a,-1);

but
Access violation reading location 0x00b21040
at this line in fourier_ndim
SWAP(data[i3+1],data[i3rev+1]);

it's something about
--- Error: expression cannot be evaluated