TD_DFFT Syntax Elements - Teradata Vantage

Teradata® VantageCloud Lake

Deployment
VantageCloud
Edition
Lake
Product
Teradata Vantage
Published
January 2023
Language
English (United States)
Last Update
2024-04-03
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SERIES_SPEC
The logical runtime time series that is passed to the TD_DFFT function as an input.

See Series Specifications.

ART_SPEC
An ART that contains the logical runtime time series that is passed to the TD_DFFT function as an input.

See ART_SPEC Syntax Elements

FUNC_PARAMS
[Optional]
Name Data Type Description
ZERO_PADDING_OK Integer [Optional] The number of zeros to add to the end of a given series to achieve a more efficient computation of the Fast Fourier Transform coefficients. A value of 1 means true, and a value of 0 means false. The default is 1. For best results, use 1.
FREQ_STYLE String [Optional] The format or values associated with the x-axis of the output. Choices are:
  • K_INTEGRAL: Integer representation.
  • K_SAMPLE_RATE: Integer normalized to number entries, with ranges from -0.5 to +0.5.
  • K_RADIANS: Radian ranges from -π to +π.
  • K_HERTZ: Frequency in hertz. Must be used in conjunction with HERTZ_SAMPLE_RATE.

The default is K_INTEGRAL.

HERTZ_SAMPLE_RATE FLOAT [Dependencies: Only used and required with the FREQ_STYLE(K_HERTZ) parameter.] The sample rate as a floating point constant, in hertz. A value of 10000.0 indicates that the sample points were obtained by sampling at a rate of 10,000 hertz.
ALGORITHM String [Optional] The user-defined algorithm that bypasses the internal DFFT planner, and influences the core DFFT algorithm associated with the primary DFFT calculation.

Choices are COOLEY_TUKEY, or SINGLETON. When this parameter is not present, then the internal DFFT planner selects the most efficient algorithm for the operation.

For best performance, do not include this parameter. Instead, let the internal DFFT planner to select the best algorithm.

HUMAN_READABLE Integer [Optional] Indicator to determine whether the produced output rows are in human-readable or plottable form, or the output is in the raw-form. Human-readable output is symmetric around 0, such as -3, -2, -1, 0, 1, 2, 3. Raw output is sequential, starting at zero, such as 0, 1, 2, 3.

A value of 1 means true, and the output is in human readable form. A value of 0 means false, and the output is in raw form. The default is 1.

INPUT_FMT
No INPUT_FMT options are available for this function.
OUTPUT_FMT

A complex number that can be in rectangular (real, imaginary) or polar (amplitude, phase) form. The output options for univariate series are the following:

  • COMPLEX
  • AMPL_PHASE_DEGREES
  • AMPL_PHASE_RADIANS

The default is COMPLEX.

The OUTPUT_FMT CONTENT output for multivariate series are the following:
  • MULTIVAR_COMPLEX
  • MULTIVAR_AMPL_PHASE_DEGREES
  • MULTIVAR_AMPL_PHASE_RADIANS
  • MULTIVAR_AMPL_PHASE

The default is MULTIVAR_COMPLEX.