Re: [R] legendre quadrature

2014-05-03 Thread Berend Hasselman 

On 01-05-2014, at 09:43, pari hesabi statistic...@hotmail.com wrote:

 Hello everybody
 I need to approximate the amount of integral by using
 legendre quadrature. I have written a program which doesn't give me a 
 logical answer; Can anybody help me and send the correct program? For 
 example  the approximated amount of integral of ( x ^2)  on (-1,1) based
 on legendre quad rule. 
 
 
 
 
 integrand-function(x) {x^2}
 rules - legendre.quadrature.rules( 50 )
 order.rule - rules[[50]]
 chebyshev.c.quadrature(integrand, order.rule, lower = -1, upper = 1) 


You must be using package gaussquad.

Why are you using Legendre rules but doing Chebyshev quadrature (which does not 
seem correct)?

Replace the last line of your given code with

legendre.quadrature(integrand, order.rule, lower = -1, upper = 1)

and the result will make more sense.

Berend

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[R] Legendre quadrature

2014-05-01 Thread pari hesabi 
Hello everybody
I need to approximate the amount of integral by using
 legendre quadrature. I have written a program which doesn't give me a 
logical answer; Can anybody help me and send the correct program? For 
example  the approximated amount of integral of ( x ^2)  on (-1,1) based
 on legendre quad rule. 
  



integrand-function(x){x^2}
rules - legendre.quadrature.rules( 50 )
order.rule - rules[[50]]
chebyshev.c.quadrature(integrand, order.rule, lower = -1, upper = 1) 

Thank you
Diba  
[[alternative HTML version deleted]]

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and provide commented, minimal, self-contained, reproducible code.

[R] legendre quadrature

2014-05-01 Thread pari hesabi 
Hello everybody
I need to approximate the amount of integral by using
 legendre quadrature. I have written a program which doesn't give me a 
logical answer; Can anybody help me and send the correct program? For 
example  the approximated amount of integral of ( x ^2)  on (-1,1) based
 on legendre quad rule. 
  



integrand-function(x) {x^2}
rules - legendre.quadrature.rules( 50 )
order.rule - rules[[50]]
chebyshev.c.quadrature(integrand, order.rule, lower = -1, upper = 1) 

Thank you
Diba
  
[[alternative HTML version deleted]]

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Re: [R] legendre quadrature

2014-05-01 Thread Prof. Dr. Matthias Kohl 

you could use package distrEx:

library(distrEx)
GLIntegrate(function(x) x^2, lower = -1, upper = 1, order = 50)

hth
Matthias

On 01.05.2014 09:43, pari hesabi wrote:

Hello everybody
I need to approximate the amount of integral by using
  legendre quadrature. I have written a program which doesn't give me a
logical answer; Can anybody help me and send the correct program? For
example  the approximated amount of integral of ( x ^2)  on (-1,1) based
  on legendre quad rule.




integrand-function(x) {x^2}
rules - legendre.quadrature.rules( 50 )
order.rule - rules[[50]]
chebyshev.c.quadrature(integrand, order.rule, lower = -1, upper = 1)

Thank you
Diba
[[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.



--
Prof. Dr. Matthias Kohl
www.stamats.de

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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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Re: [R] legendre quadrature

2014-05-01 Thread Enrico Schumann 
On Thu, 01 May 2014, pari hesabi statistic...@hotmail.com writes:

 Hello everybody
 I need to approximate the amount of integral by using
  legendre quadrature. I have written a program which doesn't give me a 
 logical answer; Can anybody help me and send the correct program? For 
 example  the approximated amount of integral of ( x ^2)  on (-1,1) based
  on legendre quad rule. 
   

One possibility:

  require(NMOF)
  xw -xwGauss(10, legendre)

  fun - function(x)
  x^2

  sum(fun(xw$nodes) * xw$weights)



 integrand-function(x) {x^2}
 rules - legendre.quadrature.rules( 50 )

  Error: object 'legendre.quadrature.rules' not found

PLEASE provide commented, minimal, self-contained, reproducible code.

 order.rule - rules[[50]]
 chebyshev.c.quadrature(integrand, order.rule, lower = -1, upper = 1) 

 Thank you
 Diba  
   

-- 
Enrico Schumann
Lucerne, Switzerland
http://enricoschumann.net

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and provide commented, minimal, self-contained, reproducible code.