private double[] DFT1DRealToComplex()
{
/* Real-to-complex 1D transform
* for double precision data
* not inplace with pack format
* Configuration parameters for MKL DFTI
* DFTI.FORWARD_DOMAIN = DFTI.REAL
* DFTI.PRECISION = DFTI.DOUBLE
* DFTI.DIMENSION = 1
* DFTI.LENGTHS = INPUT_SIZE (n)
* DFTI.PLACEMENT = DFTI.NOT_INPLACE
* DFTI.BACKWARD_SCALE = (1.0 / n) (backwardScale)
* Default values:
* DFTI.PACKED_FORMAT = DFTI.PACK_FORMAT
* DFTI.FORWARD_SCALE = 1.0
*/
IntPtr descriptor = new IntPtr();
int precision = DFTI.DOUBLE;
int forwardDomain = DFTI.REAL;
int dimension = 1;
int n = INPUT_SIZE;
// The input data to be transformed
double[] input = Generate1DInput();
// Create a new DFTI descriptor
DFTI.DftiCreateDescriptor(ref descriptor,
precision, forwardDomain, dimension, n);
// Configure DFTI.BACKWARD_SCALE
double backwardScale = 1.0 / n;
DFTI.DftiSetValue(descriptor,
DFTI.BACKWARD_SCALE,
backwardScale);
// Configure DFTI.PLACEMENT
DFTI.DftiSetValue(descriptor,
DFTI.PLACEMENT,
DFTI.NOT_INPLACE);
// Configure DFTI.PACKET_FORMAT
DFTI.DftiSetValue(descriptor,
DFTI.PACKED_FORMAT,
DFTI.PACK_FORMAT);
// Commit the descriptor with the configuration
DFTI.DftiCommitDescriptor(descriptor);
// This is the output array
double[] output = new double[n];
// Compute the forward transform
var err = DFTI.DftiComputeForward(descriptor,
input,
output);
// Free the descriptor
DFTI.DftiFreeDescriptor(ref descriptor);
if (err == DFTI.NO_ERROR)
{
return(output);
}
else
{
throw new MKLException(
String.Format("DFTI returned error code {0}",
err));
}
}
public static void Test()
{
IntPtr desc = new IntPtr();
int precision = DFTI.DOUBLE;
int forward_domain = DFTI.REAL;
int dimension = 1, length = 6;
/* The data to be transformed */
double[] x_normal = new double[length];
double[] x_transformed = new double[length];
/* Create new DFTI descriptor */
int ret = DFTI.DftiCreateDescriptor(ref desc,
precision, forward_domain, dimension, length);
Debug.WriteLine("ret = " + ret);
/* Setup the scale factor */
long transform_size = length;
double scale_factor = 1.0 / transform_size;
ret = DFTI.DftiSetValue(desc, DFTI.BACKWARD_SCALE, scale_factor);
Debug.WriteLine("ret = " + ret);
/* Try floating-point and GetValue function */
double backward_scale = 0;
ret = DFTI.DftiGetValue(desc, DFTI.BACKWARD_SCALE, ref backward_scale);
Debug.WriteLine("ret = " + ret);
Debug.WriteLine("Backward transform scale: " + backward_scale);
/* Setup the transform parameters */
ret = DFTI.DftiSetValue(desc, DFTI.PLACEMENT, DFTI.NOT_INPLACE);
Debug.WriteLine("ret = " + ret);
ret = DFTI.DftiSetValue(desc, DFTI.PACKED_FORMAT, DFTI.PACK_FORMAT);
Debug.WriteLine("ret = " + ret);
/* Commit the descriptor */
ret = DFTI.DftiCommitDescriptor(desc);
Debug.WriteLine("ret = " + ret);
/* Initialize the data array */
Debug.WriteLine("Initial data:");
for (int i = 0; i < length; i++)
{
x_normal[i] = i;
Debug.Write("\t" + i);
}
Debug.WriteLine("");
/* Forward, then backward transform */
ret = DFTI.DftiComputeForward(desc, x_normal, x_transformed);
Debug.WriteLine("ret = " + ret);
ret = DFTI.DftiComputeBackward(desc, x_transformed, x_normal);
Debug.WriteLine("ret = " + ret);
DFTI.DftiFreeDescriptor(ref desc);
/* Check the data array */
Debug.WriteLine("Resulting data:");
for (int i = 0; i < length; i++)
{
Debug.Write("\t" + x_normal[i]);
}
Debug.WriteLine("");
Debug.WriteLine("TEST PASSED");
Debug.WriteLine("");
}