Re: [R] symbolic computing example with Ryacas

[Gabor Grothendieck]

Here are some more examples:

library(Ryacas)

x <- Sym("x")
yacas("x:=2")
Eval(x*x)
## [1] 4

# vignette has similar example
y <- Sym("y")
Eval(Subst(y*y, y, 3))
## [1] 9

# demo("Ryacas-Function") has similar example to this
f <- function(z) {}
body(f) <- yacas(expression(z*z))[[1]]
f(4)
## [1] 16



On Tue, Sep 19, 2017 at 2:08 PM, Vivek Sutradhara  wrote:
> Thanks for the response. Yes, I did study the vignette but did not
> understand it fully. Anyway, I have tried once again now. I am happy to say
> that I have got what I wanted.
>
> library(Ryacas)
> x <- Sym("x");U <- Sym("U");x0 <- Sym("x0");C <- Sym("C")
> my_func <- function(x,U,x0,C) {
>   return (U/(1+exp(-(x-x0)/C)))}
> FirstDeriv <- deriv(my_func(x,U,x0,C), x)
> PrettyForm(FirstDeriv)
> #slope <- yacas("Subst(x,x0),deriv(my_func(x,U,x0,C), x)")
> slope <- Subst(FirstDeriv,x,x0)
> #PrettyForm(slope) - gives errors
> PrettyForm(Simplify(slope))
>
> I was confused by the references to the yacas command.  Now, I have chosen
> to omit it. Then I get what I want.
> Thanks,
> Vivek
>
> 2017-09-19 16:04 GMT+02:00 Bert Gunter :
>
>> Have you studied the "Introduction to Ryacas" vignette that come with the
>> package?
>>
>> Cheers,
>> Bert
>>
>>
>>
>> Bert Gunter
>>
>> "The trouble with having an open mind is that people keep coming along and
>> sticking things into it."
>> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
>>
>> On Tue, Sep 19, 2017 at 2:37 AM, Vivek Sutradhara 
>> wrote:
>>
>>> Hi all,
>>> I am trying to implement the following matlab code with Ryacas :
>>>
>>> syms U x x0 C
>>>
>>> d1=diff(U/(1+exp(-(x-x0)/C)),x);
>>>
>>> pretty(d1)
>>>
>>> d2=diff(U/(1+exp(-(x-x0)/C)),x,2);
>>>
>>> pretty(d2)
>>>
>>> solx2 = solve(d2 == 0, x, 'Real', true)
>>>
>>> pretty(solx2)
>>>
>>> slope2=subs(d1,solx2)
>>>
>>>
>>> I have tried the following :
>>>
>>> library(Ryacas)
>>>
>>> x <- Sym("x");U <- Sym("U");x0 <- Sym("x0");C <- Sym("C")
>>>
>>> my_func <- function(x,U,x0,C) {
>>>
>>>   return (U/(1+exp(-(x-x0)/C)))}
>>>
>>> FirstDeriv <- deriv(my_func(x,U,x0,C), x)
>>>
>>> PrettyForm(FirstDeriv)
>>>
>>> slope <- yacas("Subst(x,x0),deriv(my_func(x,U,x0,C), x)")
>>>
>>> PrettyForm(slope)
>>>
>>>
>>> I don't understand how I should use the Subst command. I want the slope of
>>> the first derivative at x=x0. How do I implement that?
>>>
>>> I would appreciate any help that I can get.
>>>
>>> Thanks,
>>>
>>> Vivek
>>>
>>> [[alternative HTML version deleted]]
>>>
>>> __
>>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide http://www.R-project.org/posti
>>> ng-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>>
>
> [[alternative HTML version deleted]]
>
> __
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.



-- 
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com

__
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Re: [R] symbolic computing example with Ryacas

[Vivek Sutradhara]

Thanks for the response. Yes, I did study the vignette but did not
understand it fully. Anyway, I have tried once again now. I am happy to say
that I have got what I wanted.

library(Ryacas)
x <- Sym("x");U <- Sym("U");x0 <- Sym("x0");C <- Sym("C")
my_func <- function(x,U,x0,C) {
  return (U/(1+exp(-(x-x0)/C)))}
FirstDeriv <- deriv(my_func(x,U,x0,C), x)
PrettyForm(FirstDeriv)
#slope <- yacas("Subst(x,x0),deriv(my_func(x,U,x0,C), x)")
slope <- Subst(FirstDeriv,x,x0)
#PrettyForm(slope) - gives errors
PrettyForm(Simplify(slope))

I was confused by the references to the yacas command.  Now, I have chosen
to omit it. Then I get what I want.
Thanks,
Vivek

2017-09-19 16:04 GMT+02:00 Bert Gunter :

> Have you studied the "Introduction to Ryacas" vignette that come with the
> package?
>
> Cheers,
> Bert
>
>
>
> Bert Gunter
>
> "The trouble with having an open mind is that people keep coming along and
> sticking things into it."
> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
>
> On Tue, Sep 19, 2017 at 2:37 AM, Vivek Sutradhara 
> wrote:
>
>> Hi all,
>> I am trying to implement the following matlab code with Ryacas :
>>
>> syms U x x0 C
>>
>> d1=diff(U/(1+exp(-(x-x0)/C)),x);
>>
>> pretty(d1)
>>
>> d2=diff(U/(1+exp(-(x-x0)/C)),x,2);
>>
>> pretty(d2)
>>
>> solx2 = solve(d2 == 0, x, 'Real', true)
>>
>> pretty(solx2)
>>
>> slope2=subs(d1,solx2)
>>
>>
>> I have tried the following :
>>
>> library(Ryacas)
>>
>> x <- Sym("x");U <- Sym("U");x0 <- Sym("x0");C <- Sym("C")
>>
>> my_func <- function(x,U,x0,C) {
>>
>>   return (U/(1+exp(-(x-x0)/C)))}
>>
>> FirstDeriv <- deriv(my_func(x,U,x0,C), x)
>>
>> PrettyForm(FirstDeriv)
>>
>> slope <- yacas("Subst(x,x0),deriv(my_func(x,U,x0,C), x)")
>>
>> PrettyForm(slope)
>>
>>
>> I don't understand how I should use the Subst command. I want the slope of
>> the first derivative at x=x0. How do I implement that?
>>
>> I would appreciate any help that I can get.
>>
>> Thanks,
>>
>> Vivek
>>
>> [[alternative HTML version deleted]]
>>
>> __
>> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posti
>> ng-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>

[[alternative HTML version deleted]]

__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Re: [R] symbolic computing example with Ryacas

[Bert Gunter]

Have you studied the "Introduction to Ryacas" vignette that come with the
package?

Cheers,
Bert



Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )

On Tue, Sep 19, 2017 at 2:37 AM, Vivek Sutradhara 
wrote:

> Hi all,
> I am trying to implement the following matlab code with Ryacas :
>
> syms U x x0 C
>
> d1=diff(U/(1+exp(-(x-x0)/C)),x);
>
> pretty(d1)
>
> d2=diff(U/(1+exp(-(x-x0)/C)),x,2);
>
> pretty(d2)
>
> solx2 = solve(d2 == 0, x, 'Real', true)
>
> pretty(solx2)
>
> slope2=subs(d1,solx2)
>
>
> I have tried the following :
>
> library(Ryacas)
>
> x <- Sym("x");U <- Sym("U");x0 <- Sym("x0");C <- Sym("C")
>
> my_func <- function(x,U,x0,C) {
>
>   return (U/(1+exp(-(x-x0)/C)))}
>
> FirstDeriv <- deriv(my_func(x,U,x0,C), x)
>
> PrettyForm(FirstDeriv)
>
> slope <- yacas("Subst(x,x0),deriv(my_func(x,U,x0,C), x)")
>
> PrettyForm(slope)
>
>
> I don't understand how I should use the Subst command. I want the slope of
> the first derivative at x=x0. How do I implement that?
>
> I would appreciate any help that I can get.
>
> Thanks,
>
> Vivek
>
> [[alternative HTML version deleted]]
>
> __
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/
> posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

[[alternative HTML version deleted]]

__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

[R] symbolic computing example with Ryacas

[Vivek Sutradhara]

Hi all,
I am trying to implement the following matlab code with Ryacas :

syms U x x0 C

d1=diff(U/(1+exp(-(x-x0)/C)),x);

pretty(d1)

d2=diff(U/(1+exp(-(x-x0)/C)),x,2);

pretty(d2)

solx2 = solve(d2 == 0, x, 'Real', true)

pretty(solx2)

slope2=subs(d1,solx2)


I have tried the following :

library(Ryacas)

x <- Sym("x");U <- Sym("U");x0 <- Sym("x0");C <- Sym("C")

my_func <- function(x,U,x0,C) {

  return (U/(1+exp(-(x-x0)/C)))}

FirstDeriv <- deriv(my_func(x,U,x0,C), x)

PrettyForm(FirstDeriv)

slope <- yacas("Subst(x,x0),deriv(my_func(x,U,x0,C), x)")

PrettyForm(slope)


I don't understand how I should use the Subst command. I want the slope of
the first derivative at x=x0. How do I implement that?

I would appreciate any help that I can get.

Thanks,

Vivek

[[alternative HTML version deleted]]

__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.