Urgent....D operator in matlab
in [Matlab]
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From: kumar vishwajeet on 6 Apr 2010 22:00 TideMan <mulgor(a)gmail.com> wrote in message <b94018b6-814f-473c-8316-990881bdac94(a)w17g2000yqj.googlegroups.com>... > On Apr 7, 1:08 pm, "kumar vishwajeet" <kwz...(a)gmail.com> wrote: > > TideMan <mul...(a)gmail.com> wrote in message <b787b93d-3173-4ca1-9a48-d75f6afa6...(a)r1g2000yqb.googlegroups.com>... > > > On Apr 7, 12:36 pm, "kumar vishwajeet" <kwz...(a)gmail.com> wrote: > > > > Does anyone know about differential operator in MATLAB corresponding to "D" operator in Mathematica. I am not looking for diff() function. I just want to use d/dt corresponding to "d/dx" used in mathematica. I want to use this "d/dt" operator in Bessel function: > > > > 1+sigma*D/alpha^2 > > > > where D is the differential opeartor "d/dt" > > > > > I know nothing about Mathematica, but to numerically differentiate in > > > Matlab, use: > > > help diff > > > help gradient > > > > > BTW, your equation makes no sense to me. > > > By my way of reckoning, D must have an argument of some sort. > > > > A bessel function ratio is defined as following: > > B = 1 > > for ctr = 1:inf %here inf can be replaced with any finite number for approximation > > num = 1+sigma*D/(alpha1(ctr)*alpha1(ctr)) > > den = 1+sigma*D/(alpha0(ctr)*alpha0(ctr)) > > B = B*num/den > > end > > > > alpha0 and alpha1 are zeros of zero - order and first order bessel function. > > The final value of B is the bessel function ratio that I am trying to calculate. > > So when you write: > D/(alpha1(ctr)*alpha1(ctr)) > you don't mean the quotient of D and (alpha1(ctr)*alpha1(ctr)), > you mean the derivative of (alpha1(ctr)*alpha1(ctr)) with respect to > t. > Is that correct? > If so, that's pretty weird notation. > > And are you trying to differentiate (alpha1(ctr)*alpha1(ctr)) > numerically or symbolically? No I am not trying to divide or differentiate (alpha1(ctr)*alpha1(ctr)). The following expansion will make it clear:- 1+a1*d/dx+a2*(d/dx)^2+a3*(d/dx)^3+a4*(d/dx)^4+...........till infinity can be written as: 1+a1*D+a2*D+a3*D+................ till infinity where ai = sigma/(alpha1(ctr)*alpha1(ctr)) So I am trying to find a replacement for D in MATLAB.
From: kumar vishwajeet on 6 Apr 2010 22:27 "kumar vishwajeet" <kwzeet(a)gmail.com> wrote in message <hpgovk$pd4$1(a)fred.mathworks.com>... > TideMan <mulgor(a)gmail.com> wrote in message <b94018b6-814f-473c-8316-990881bdac94(a)w17g2000yqj.googlegroups.com>... > > On Apr 7, 1:08 pm, "kumar vishwajeet" <kwz...(a)gmail.com> wrote: > > > TideMan <mul...(a)gmail.com> wrote in message <b787b93d-3173-4ca1-9a48-d75f6afa6...(a)r1g2000yqb.googlegroups.com>... > > > > On Apr 7, 12:36 pm, "kumar vishwajeet" <kwz...(a)gmail.com> wrote: > > > > > Does anyone know about differential operator in MATLAB corresponding to "D" operator in Mathematica. I am not looking for diff() function. I just want to use d/dt corresponding to "d/dx" used in mathematica. I want to use this "d/dt" operator in Bessel function: > > > > > 1+sigma*D/alpha^2 > > > > > where D is the differential opeartor "d/dt" > > > > > > > I know nothing about Mathematica, but to numerically differentiate in > > > > Matlab, use: > > > > help diff > > > > help gradient > > > > > > > BTW, your equation makes no sense to me. > > > > By my way of reckoning, D must have an argument of some sort. > > > > > > A bessel function ratio is defined as following: > > > B = 1 > > > for ctr = 1:inf %here inf can be replaced with any finite number for approximation > > > num = 1+sigma*D/(alpha1(ctr)*alpha1(ctr)) > > > den = 1+sigma*D/(alpha0(ctr)*alpha0(ctr)) > > > B = B*num/den > > > end > > > > > > alpha0 and alpha1 are zeros of zero - order and first order bessel function. > > > The final value of B is the bessel function ratio that I am trying to calculate. > > > > So when you write: > > D/(alpha1(ctr)*alpha1(ctr)) > > you don't mean the quotient of D and (alpha1(ctr)*alpha1(ctr)), > > you mean the derivative of (alpha1(ctr)*alpha1(ctr)) with respect to > > t. > > Is that correct? > > If so, that's pretty weird notation. > > > > And are you trying to differentiate (alpha1(ctr)*alpha1(ctr)) > > numerically or symbolically? > > No I am not trying to divide or differentiate (alpha1(ctr)*alpha1(ctr)). The following expansion will make it clear:- > 1+a1*d/dx+a2*(d/dx)^2+a3*(d/dx)^3+a4*(d/dx)^4+...........till infinity can be written as: > 1+a1*D+a2*D^2+a3*D^3+................ till infinity > where ai = sigma/(alpha1(ctr)*alpha1(ctr)) > So I am trying to find a replacement for D in MATLAB.
From: kumar vishwajeet on 6 Apr 2010 22:28 "kumar vishwajeet" <kwzeet(a)gmail.com> wrote in message <hpgovk$pd4$1(a)fred.mathworks.com>... > TideMan <mulgor(a)gmail.com> wrote in message <b94018b6-814f-473c-8316-990881bdac94(a)w17g2000yqj.googlegroups.com>... > > On Apr 7, 1:08 pm, "kumar vishwajeet" <kwz...(a)gmail.com> wrote: > > > TideMan <mul...(a)gmail.com> wrote in message <b787b93d-3173-4ca1-9a48-d75f6afa6...(a)r1g2000yqb.googlegroups.com>... > > > > On Apr 7, 12:36 pm, "kumar vishwajeet" <kwz...(a)gmail.com> wrote: > > > > > Does anyone know about differential operator in MATLAB corresponding to "D" operator in Mathematica. I am not looking for diff() function. I just want to use d/dt corresponding to "d/dx" used in mathematica. I want to use this "d/dt" operator in Bessel function: > > > > > 1+sigma*D/alpha^2 > > > > > where D is the differential opeartor "d/dt" > > > > > > > I know nothing about Mathematica, but to numerically differentiate in > > > > Matlab, use: > > > > help diff > > > > help gradient > > > > > > > BTW, your equation makes no sense to me. > > > > By my way of reckoning, D must have an argument of some sort. > > > > > > A bessel function ratio is defined as following: > > > B = 1 > > > for ctr = 1:inf %here inf can be replaced with any finite number for approximation > > > num = 1+sigma*D/(alpha1(ctr)*alpha1(ctr)) > > > den = 1+sigma*D/(alpha0(ctr)*alpha0(ctr)) > > > B = B*num/den > > > end > > > > > > alpha0 and alpha1 are zeros of zero - order and first order bessel function. > > > The final value of B is the bessel function ratio that I am trying to calculate. > > > > So when you write: > > D/(alpha1(ctr)*alpha1(ctr)) > > you don't mean the quotient of D and (alpha1(ctr)*alpha1(ctr)), > > you mean the derivative of (alpha1(ctr)*alpha1(ctr)) with respect to > > t. > > Is that correct? > > If so, that's pretty weird notation. > > > > And are you trying to differentiate (alpha1(ctr)*alpha1(ctr)) > > numerically or symbolically? > > No I am not trying to divide or differentiate (alpha1(ctr)*alpha1(ctr)). The following expansion will make it clear:- > 1+a1*d/dx+a2*(d/dx)^2+a3*(d/dx)^3+a4*(d/dx)^4+...........till infinity can be written as: > 1+a1*D+a2*D+a3*D+................ till infinity > where ai = sigma/(alpha1(ctr)*alpha1(ctr)) > So I am trying to find a replacement for D in MATLAB. Sorry..I mean 1+a1*D+a2*D^2+a3*D^3+................ till infinity
From: Steven Lord on 7 Apr 2010 10:22 "kumar vishwajeet" <kwzeet(a)gmail.com> wrote in message news:hpgqjn$gv4$1(a)fred.mathworks.com... > "kumar vishwajeet" <kwzeet(a)gmail.com> wrote in message > <hpgovk$pd4$1(a)fred.mathworks.com>... >> TideMan <mulgor(a)gmail.com> wrote in message >> <b94018b6-814f-473c-8316-990881bdac94(a)w17g2000yqj.googlegroups.com>... >> > On Apr 7, 1:08 pm, "kumar vishwajeet" <kwz...(a)gmail.com> wrote: >> > > TideMan <mul...(a)gmail.com> wrote in message >> > > <b787b93d-3173-4ca1-9a48-d75f6afa6...(a)r1g2000yqb.googlegroups.com>... >> > > > On Apr 7, 12:36 pm, "kumar vishwajeet" <kwz...(a)gmail.com> wrote: >> > > > > Does anyone know about differential operator in MATLAB >> > > > > corresponding to "D" operator in Mathematica. I am not looking >> > > > > for diff() function. I just want to use d/dt corresponding to >> > > > > "d/dx" used in mathematica. I want to use this "d/dt" operator in >> > > > > Bessel function: >> > > > > 1+sigma*D/alpha^2 >> > > > > where D is the differential opeartor "d/dt" >> > > >> > > > I know nothing about Mathematica, but to numerically differentiate >> > > > in >> > > > Matlab, use: >> > > > help diff >> > > > help gradient >> > > >> > > > BTW, your equation makes no sense to me. >> > > > By my way of reckoning, D must have an argument of some sort. >> > > >> > > A bessel function ratio is defined as following: >> > > B = 1 >> > > for ctr = 1:inf %here inf can be replaced with any finite number for >> > > approximation >> > > num = 1+sigma*D/(alpha1(ctr)*alpha1(ctr)) >> > > den = 1+sigma*D/(alpha0(ctr)*alpha0(ctr)) >> > > B = B*num/den >> > > end >> > > >> > > alpha0 and alpha1 are zeros of zero - order and first order bessel >> > > function. >> > > The final value of B is the bessel function ratio that I am trying to >> > > calculate. >> > >> > So when you write: >> > D/(alpha1(ctr)*alpha1(ctr)) >> > you don't mean the quotient of D and (alpha1(ctr)*alpha1(ctr)), >> > you mean the derivative of (alpha1(ctr)*alpha1(ctr)) with respect to >> > t. >> > Is that correct? >> > If so, that's pretty weird notation. >> > >> > And are you trying to differentiate (alpha1(ctr)*alpha1(ctr)) >> > numerically or symbolically? >> >> No I am not trying to divide or differentiate (alpha1(ctr)*alpha1(ctr)). >> The following expansion will make it clear:- >> 1+a1*d/dx+a2*(d/dx)^2+a3*(d/dx)^3+a4*(d/dx)^4+...........till infinity >> can be written as: >> 1+a1*D+a2*D+a3*D+................ till infinity >> where ai = sigma/(alpha1(ctr)*alpha1(ctr)) >> So I am trying to find a replacement for D in MATLAB. > > Sorry..I mean > 1+a1*D+a2*D^2+a3*D^3+................ till infinity You can't have just a "naked" derivative operator -- you have to apply it to some function. If you have a symbolic function created using Symbolic Math Toolbox, then DIFF is the correct function to use ... as long as you use it on a sym object, which will invoke the DIFF _method_ for sym objects rather than the numeric DIFF _function_ which computes a difference. syms t f = sin(t)+cos(t); derivative = f; % the "0th" derivative is F itself n = 20; a = 1:n; total = sym(ones(1, n+1)); for k = 1:n derivative = diff(derivative, t); total(k+1) = a(k)*derivative; end sumOfDerivatives = sum(total) Note I've done it this way so you can see each term that contributes to the sum -- if you want you can simply add each term to the running total inside the loop. Note that if you want you could put this code in a function that accepts f and the symbolic variable with which to differentiate; that way you could apply it like the "naked" (1+sum(a(k)*D^k)) operator you described above. -- Steve Lord slord(a)mathworks.com comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ
From: Loren Shure on 7 Apr 2010 12:03 In article <hpgk25$igs$1(a)fred.mathworks.com>, kwzeet(a)gmail.com says... > Does anyone know about differential operator in MATLAB corresponding to "D" operator in Mathematica. I am not looking for diff() function. I just want to use d/dt corresponding to "d/dx" used in mathematica. I want to use this "d/dt" operator in Bessel function: > 1+sigma*D/alpha^2 > where D is the differential opeartor "d/dt" > Perhaps you can use diff on a sym object from the Symbolic Math Toolbox. -- Loren http://blogs.mathworks.com/loren http://matlabwiki.mathworks.com/MATLAB_FAQ
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