Describe this function?
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From: Tim Foe on 17 Jun 2010 16:04 I'm looking for a simple way to describe the following function: 10 1 ..1 ..01 ..001 0 -.001 -.01 -.1 -1 -10 it's sort of like a sigmoid but rotated
From: Virgil on 17 Jun 2010 18:47 In article <b9982864-5eb3-4398-812b-218a9f17a31d(a)y4g2000yqy.googlegroups.com>, Tim Foe <timfoea(a)gmail.com> wrote: > I'm looking for a simple way to describe the following function: > > 10 > 1 > .1 > .01 > .001 > 0 > -.001 > -.01 > -.1 > -1 > -10 > > it's sort of like a sigmoid but rotated "Function"? How is what you posted a function? All I see is a finite list of reals. What is the domain of your function ( the set of arguments for which the function determines values)? Is it the poistion in the list? What is the range of your function? Is it {10, 1, .1, .01. ,001, 0, -.001, -.01, -.1, -1. 10} ?
From: James Waldby on 17 Jun 2010 19:20 On Thu, 17 Jun 2010 13:04:55 -0700, Tim Foe wrote: > I'm looking for a simple way to describe the following function: > > 10 > 1 > .1 > .01 > .001 > 0 > -.001 > -.01 > -.1 > -1 > -10 > > it's sort of like a sigmoid but rotated As Virgil noted, you should have specified domain and range values. Assuming people somehow will know what you mean isn't bright. Anyhow, if those are readings y_i taken at times x_i with delta x constant, then the semi-log graph of abs(y_i) vs x_i is slightly reminiscent of a chevron plot, as seen at <http://en.wikipedia.org/wiki/Chevron_plot> -- jiw
From: Tim Foe on 18 Jun 2010 00:15 sorry, i need a function that relates an array such as: from 1 to 10 or from 0.1 to 1 step .1 to the array i listed originally thanks On Jun 17, 6:20 pm, James Waldby <n...(a)no.no> wrote: > On Thu, 17 Jun 2010 13:04:55 -0700, Tim Foe wrote: > > I'm looking for a simple way to describe the following function: > > > 10 > > 1 > > .1 > > .01 > > .001 > > 0 > > -.001 > > -.01 > > -.1 > > -1 > > -10 > > > it's sort of like a sigmoid but rotated > > As Virgil noted, you should have specified domain and range > values. Assuming people somehow will know what you mean > isn't bright. > > Anyhow, if those are readings y_i taken at times x_i with > delta x constant, then the semi-log graph of abs(y_i) vs x_i > is slightly reminiscent of a chevron plot, as seen at > <http://en.wikipedia.org/wiki/Chevron_plot> > > -- > jiw
From: James Waldby on 18 Jun 2010 11:36
On Thu, 17 Jun 2010 21:15:56 -0700, Tim Foe wrote: [top posting corrected] >On Jun 17, 6:20pm, James Waldby wrote: >> On Thu, 17 Jun 2010 13:04:55 -0700, Tim Foe wrote: >> > I'm looking for a simple way to describe the following function: >> > 10 >> > 1 >> > .1 >> > .01 >> > .001 >> > 0 >> > -.001 >> > -.01 >> > -.1 >> > -1 >> > -10 >> > it's sort of like a sigmoid but rotated .... >> Anyhow, if those are readings y_i taken at times x_i with >> delta x constant, then the semi-log graph of abs(y_i) vs x_i >> is slightly reminiscent of a chevron plot, as seen at >> <http://en.wikipedia.org/wiki/Chevron_plot> > >sorry, i need a function that relates an array such as: > >from 1 to 10 > >or > >from 0.1 to 1 step .1 > >to the array i listed originally Please don't top post. I've moved your text to the end. You could try -signum(x-5) * 10^{ abs(x-5)-3 }, where signum and abs are as at <http://en.wikipedia.org/wiki/Sign_function> and <http://en.wikipedia.org/wiki/Absolute_value>. -- jiw |