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Nam Lethanh

2010-Aug-30 05:27 UTC

[R] LOOping problem with R

Dear Guys,

I do converting codes from Fortran into R and got stuck in solving LOOPING
procedure with R. In FORTRAN, it is (DO and END DO) for looping in the net.
In R, it is (FOR with {   }).

I believe there is something wrong with my coding in R, do hope that you can
help me solving following problems.

It seems easy, but results are not the same.

***************************************************************************
WITH R

theta<-c(0.08,0.06,0.09,0)
for (i in 1:4){
for (j in 1:4){
a<-1.0
for (k in i:(j-1)){
a<-a*theta[k]
}
print(a)
}
--------------------------------------------------------------------------------------
HERE GOES the results
-------------------------
numeric(0)
[1] 0.08
[1] 0.0048
[1] 0.000432
numeric(0)
[1] 0.0048
[1] 0.06
[1] 0.0054
numeric(0)
[1] 0.000432
[1] 0.0054
[1] 0.09
numeric(0)
[1] 0
[1] 0
[1] 0
*********************************************************************************
IN FORTRAN, the results is totally different.

program calculating_a
implicit none
integer i, j, k
double precision a, theta(4)
theta(1)=0.06; theta(2)=0.08; theta(3)=0.09; theta(4)=0
do i=1, 4
do j=1, 4
a=1
do k=i,j-1
a=a*theta(k)
end do

print*, a

end do
end do
end

Here goes the results with FOTRAN

-------------------------------------------------------------------------------------
1
0.06
4.79E-003
4.31E-004
1
1
0.08
7.2E-0.03
1
1
1
0.09
1
1
1
1
-----------------------------------------------------------------------------



Thank you!



Nam

	[[alternative HTML version deleted]]

David Winsemius

2010-Aug-30 06:33 UTC

head link

[R] LOOping problem with R

On Aug 30, 2010, at 1:27 AM, Nam Lethanh wrote:
> Dear Guys,
>
> I do converting codes from Fortran into R and got stuck in solving  
> LOOPING
> procedure with R. In FORTRAN, it is (DO and END DO) for looping in  
> the net.
> In R, it is (FOR with {   }).
Looking at the results  (namely  the 1's from the fortran code) it  
appears there are some conditions that cause FORTRAN not to enter the  
loop whereas in R the inner loop is always entered. The numeric(0)'s  
occur when you attempt to use a zero as an index. If you have a more  
specific question about what the indices are at times that surprise,  
then maybe you ought to put in more debugging code.
>
> I believe there is something wrong with my coding in R, do hope that  
> you can
> help me solving following problems.
>
> It seems easy, but results are not the same.
>
> ***************************************************************************
> WITH R
>
> theta<-c(0.08,0.06,0.09,0)
> for (i in 1:4){
> for (j in 1:4){
> a<-1.0
> for (k in i:(j-1)){
> a<-a*theta[k]
> }
> print(a)
> }
>
--------------------------------------------------------------------------------------
> HERE GOES the results
> -------------------------
> numeric(0)
> [1] 0.08
> [1] 0.0048
> [1] 0.000432
> numeric(0)
> [1] 0.0048
> [1] 0.06
> [1] 0.0054
> numeric(0)
> [1] 0.000432
> [1] 0.0054
> [1] 0.09
> numeric(0)
> [1] 0
> [1] 0
> [1] 0
>
*********************************************************************************
> IN FORTRAN, the results is totally different.
>
> program calculating_a
> implicit none
> integer i, j, k
> double precision a, theta(4)
> theta(1)=0.06; theta(2)=0.08; theta(3)=0.09; theta(4)=0
> do i=1, 4
> do j=1, 4
> a=1
> do k=i,j-1
> a=a*theta(k)
> end do
>
> print*, a
>
> end do
> end do
> end
>
> Here goes the results with FOTRAN
>
>
-------------------------------------------------------------------------------------
> 1
> 0.06
> 4.79E-003
> 4.31E-004
> 1
> 1
> 0.08
> 7.2E-0.03
> 1
> 1
> 1
> 0.09
> 1
> 1
> 1
> 1
>
-----------------------------------------------------------------------------
>
>
>
> Thank you!
>
>
>
> Nam
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.

Mario Valle

2010-Aug-30 06:34 UTC

head link

[R] LOOping problem with R

When j==1 for loops from i down to zero. 5:0 is valid and means c(5,4,3,2,1,0)
Hope it helps
			mario

Nam Lethanh wrote:> Dear Guys,
> 
> I do converting codes from Fortran into R and got stuck in solving LOOPING
> procedure with R. In FORTRAN, it is (DO and END DO) for looping in the net.
> In R, it is (FOR with {   }).
> 
> I believe there is something wrong with my coding in R, do hope that you
can
> help me solving following problems.
> 
> It seems easy, but results are not the same.
> 
> ***************************************************************************
> WITH R
> 
> theta<-c(0.08,0.06,0.09,0)
> for (i in 1:4){
> for (j in 1:4){
> a<-1.0
> for (k in i:(j-1)){
> a<-a*theta[k]
> }
> print(a)
> }
>
--------------------------------------------------------------------------------------
> HERE GOES the results
> -------------------------
> numeric(0)
> [1] 0.08
> [1] 0.0048
> [1] 0.000432
> numeric(0)
> [1] 0.0048
> [1] 0.06
> [1] 0.0054
> numeric(0)
> [1] 0.000432
> [1] 0.0054
> [1] 0.09
> numeric(0)
> [1] 0
> [1] 0
> [1] 0
>
*********************************************************************************
> IN FORTRAN, the results is totally different.
> 
> program calculating_a
> implicit none
> integer i, j, k
> double precision a, theta(4)
> theta(1)=0.06; theta(2)=0.08; theta(3)=0.09; theta(4)=0
> do i=1, 4
> do j=1, 4
> a=1
> do k=i,j-1
> a=a*theta(k)
> end do
> 
> print*, a
> 
> end do
> end do
> end
> 
> Here goes the results with FOTRAN
> 
>
-------------------------------------------------------------------------------------
> 1
> 0.06
> 4.79E-003
> 4.31E-004
> 1
> 1
> 0.08
> 7.2E-0.03
> 1
> 1
> 1
> 0.09
> 1
> 1
> 1
> 1
>
-----------------------------------------------------------------------------
> 
> 
> 
> Thank you!
> 
> 
> 
> Nam
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list
> 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.
-- 
Ing. Mario Valle
Data Analysis and Visualization Group            | http://www.cscs.ch/~mvalle
Swiss National Supercomputing Centre (CSCS)      | Tel:  +41 (91) 610.82.60
v. Cantonale Galleria 2, 6928 Manno, Switzerland | Fax:  +41 (91) 610.82.82

Joshua Wiley

2010-Aug-30 06:50 UTC

head link

[R] LOOping problem with R

Hi,

I would also like to point out that you flipped the first two the
values of theta in the R vs. FORTRAN versions.  This fixes part of
your differences (and makes it easy to see that the differences occur
when j < i, as David and Mario point out).

Josh

On Sun, Aug 29, 2010 at 10:27 PM, Nam Lethanh <namkyodai at gmail.com>
wrote:> Dear Guys,
>
> I do converting codes from Fortran into R and got stuck in solving LOOPING
> procedure with R. In FORTRAN, it is (DO and END DO) for looping in the net.
> In R, it is (FOR with { ? }).
>
> I believe there is something wrong with my coding in R, do hope that you
can
> help me solving following problems.
>
> It seems easy, but results are not the same.
>
> ***************************************************************************
> WITH R
>
> theta<-c(0.08,0.06,0.09,0)
> for (i in 1:4){
> for (j in 1:4){
> a<-1.0
> for (k in i:(j-1)){
> a<-a*theta[k]
> }
> print(a)
> }
>
--------------------------------------------------------------------------------------
> HERE GOES the results
> -------------------------
> numeric(0)
> [1] 0.08
> [1] 0.0048
> [1] 0.000432
> numeric(0)
> [1] 0.0048
> [1] 0.06
> [1] 0.0054
> numeric(0)
> [1] 0.000432
> [1] 0.0054
> [1] 0.09
> numeric(0)
> [1] 0
> [1] 0
> [1] 0
>
*********************************************************************************
> IN FORTRAN, the results is totally different.
>
> program calculating_a
> implicit none
> integer i, j, k
> double precision a, theta(4)
> theta(1)=0.06; theta(2)=0.08; theta(3)=0.09; theta(4)=0
> do i=1, 4
> do j=1, 4
> a=1
> do k=i,j-1
> a=a*theta(k)
> end do
>
> print*, a
>
> end do
> end do
> end
>
> Here goes the results with FOTRAN
>
>
-------------------------------------------------------------------------------------
> 1
> 0.06
> 4.79E-003
> 4.31E-004
> 1
> 1
> 0.08
> 7.2E-0.03
> 1
> 1
> 1
> 0.09
> 1
> 1
> 1
> 1
>
-----------------------------------------------------------------------------
>
>
>
> Thank you!
>
>
>
> Nam
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.
>


-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/

Berend Hasselman

2010-Aug-30 08:07 UTC

head link

[R] LOOping problem with R

You made a mistake with theta

theta<-c(0.08,0.06,0.09,0)

This should be (see the fortran)

theta<-c(0.06,0.08,0.09,0)

The innermost loop (for( k in ...) is better written as while loop to take
into account how Fortran handles loops (see the previous replies):

        k <- i
        while( k <= j-1 ){
           a<-a*theta[k]
           k <- k + 1
        }

Berend



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