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# Differences

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making_the_blackfin_perform [2010/11/29 22:01]
lastman [Example - Dot Product] grammar fixes
making_the_blackfin_perform [2010/11/29 22:08] (current)
lastman [Example - FFT] grammar fixes
 Line 113: Line 113: ===== Example - FFT ===== ===== Example - FFT ===== - Another good example of a of a commonly used function is the [[wp>Fast_Fourier_transform|Fast Fourier Transform]] (FFT). It is an efficient algorithm to compute the discrete Fourier transform (DFT) and its inverse. FFTs are of great importance to a wide variety of applications, from signal processing to solving partial differential equations to algorithms for quickly multiplying large integers. + Another good example of a commonly used function is the [[wp>Fast_Fourier_transform|Fast Fourier Transform]] (FFT). It is an efficient algorithm to compute the discrete Fourier transform (DFT) and its inverse. FFTs are of great importance to a wide variety of applications, from signal processing to solving partial differential equations to algorithms for quickly multiplying large integers. If x = x_0, x_1,{cdots},~x_n of complex numbers, the DFT is:\\ If x = x_0, x_1,{cdots},~x_n of complex numbers, the DFT is:\\ Line 122: Line 122: There are many ways and algorithms to calculate an FFT, [[wp>Cooley-Tukey_FFT_algorithm|Cooley Tukey]] being one of the most common. There are many ways and algorithms to calculate an FFT, [[wp>Cooley-Tukey_FFT_algorithm|Cooley Tukey]] being one of the most common. - A C implementation is show at:? + A C implementation is shown at:? Line 130: Line 130: - A alternative solution is to use the fft function in the libbfdsp library: + An alternative solution is to use the fft function in the libbfdsp library: Line 145: Line 145: - The two different functions are the functionally equivalent, but from a performance standpoint, it is more than a 50x difference. Using the built in functions, take only 18,400 cycles. + The two different functions are functionally equivalent, but from a performance standpoint, there is more than 50x difference. Using the built in function takes only 18,400 cycles. As another point of reference the following link points to a page which optimizes an FFT with intrinsics and inline assembler. [[example-builtin]] As another point of reference the following link points to a page which optimizes an FFT with intrinsics and inline assembler. [[example-builtin]] 