symmetric 2D function....
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From: fisico32 on 28 May 2010 08:43 Hello Forum, I am dealing with a 2D function of time. A 1D function f(t) is symmetric and even if f(t)=f(-t) I am dealing with a function f(t1,t2) instead for which f(t1,t2)=f(-t1, -t2). In the plane t1-t2, how many possible symmetries with respect to vertical planes can a function like f(t1,t2) have? I guess it depends on the function. Is there a way using combinatorics to find out the various combinations of the arguments t1,t2 to determine if the function is "even"? What does the concept of "even" function mean in 2D? thanks, fisico
From: dbd on 28 May 2010 09:55 On May 28, 5:43 am, "fisico32" <marcoscipioni1(a)n_o_s_p_a_m.gmail.com> wrote: > Hello Forum, > > I am dealing with a 2D function of time. A 1D function f(t) is symmetric > and even if f(t)=f(-t) > ... > What does the concept of "even" function mean in 2D? > > thanks, > fisico Is your question a (continuous/infinite) theoretical one or do you want a (sampled/finite) DSP answer? Your first sentence is not true in the finite sampled domain for some definitions of even. Dale B. Dalrymple
From: Dirk Bell on 28 May 2010 10:30 On May 28, 8:43 am, "fisico32" <marcoscipioni1(a)n_o_s_p_a_m.gmail.com> wrote: > Hello Forum, > > I am dealing with a 2D function of time. A 1D function f(t) is symmetric > and even if f(t)=f(-t) > > I am dealing with a function f(t1,t2) instead for which > > f(t1,t2)=f(-t1, -t2). > > In the plane t1-t2, how many possible symmetries with respect to vertical > planes can a function like f(t1,t2) have? > I guess it depends on the function. Is there a way using combinatorics to > find out the various combinations of the arguments t1,t2 to determine if > the function is "even"? > > What does the concept of "even" function mean in 2D? > > thanks, > fisico Think in terms of symmetric "about" something. A number of obvious symmetries can be defined for 2-D. BTW for 1-D, what you described is even symmetic about the origin. Dirk
From: Tim Wescott on 28 May 2010 14:19 On 05/28/2010 06:55 AM, dbd wrote: > On May 28, 5:43 am, "fisico32"<marcoscipioni1(a)n_o_s_p_a_m.gmail.com> > wrote: >> Hello Forum, >> >> I am dealing with a 2D function of time. A 1D function f(t) is symmetric >> and even if f(t)=f(-t) >> ... > >> What does the concept of "even" function mean in 2D? >> >> thanks, >> fisico > > Is your question a (continuous/infinite) theoretical one or do you > want a (sampled/finite) DSP answer? Your first sentence is not true in > the finite sampled domain for some definitions of even. Which ones? Examples? AFAIK it's a universally accepted definition. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
From: dbd on 28 May 2010 17:50
On May 28, 11:19 am, Tim Wescott <t...(a)seemywebsite.now> wrote: > On 05/28/2010 06:55 AM, dbd wrote: > > > On May 28, 5:43 am, "fisico32"<marcoscipioni1(a)n_o_s_p_a_m.gmail.com> > > wrote: > >> ... > >> fisico > > Is your question a (continuous/infinite) theoretical one or do you > > want a (sampled/finite) DSP answer? Your first sentence is not true in > > the finite sampled domain for some definitions of even. > Which ones? Examples? AFAIK it's a universally accepted definition. > Tim Wescott DFT-even Dale B. Dalrymple |