search for: jmax

I'm doing convolutions in the frequency domain and need to know the layout of the Fourier modes returned by fft. (This is leading up to a more involved question about moment generating functions, but I need to know if I've got this part correct first.) I think in 1D the pattern is: 0 1 2 3 -2 1 (even) 0 1 2 3 -3 2 1 (odd) In 2D is it simply (for a square matrix): 0 1 2 -1 (horizontal)

...ticed that LLVM does a bad job of optimizing array indexing > code for FORTRAN arrays declared using the ALLOCATABLE keyword. > > For example if you have something like the following: > > DOUBLE PRECISION,ALLOCATABLE,DIMENSION(:,:,:,:) :: QAV > ... > ALLOCATE( QAV( -2:IMAX+2,-2:JMAX+2,-2:KMAX+2,ND) ) > ... > DO L = 1, 5 > DO K = K1, K2 > DO J = J1, J2 > DO I = I1, I2 > II = I + IADD > IBD = II - IBDD > ICD = II + IBDD > > QAV(I,J,K,L) = R6I * (2.0D0 * Q(IBD,J,K,L,N) + >&...

I've noticed that LLVM does a bad job of optimizing array indexing code for FORTRAN arrays declared using the ALLOCATABLE keyword. For example if you have something like the following: DOUBLE PRECISION,ALLOCATABLE,DIMENSION(:,:,:,:) :: QAV ... ALLOCATE( QAV( -2:IMAX+2,-2:JMAX+2,-2:KMAX+2,ND) ) ... DO L = 1, 5 DO K = K1, K2 DO J = J1, J2 DO I = I1, I2 II = I + IADD IBD = II - IBDD ICD = II + IBDD QAV(I,J,K,L) = R6I * (2.0D0 * Q(IBD,J,K,L,N) + > 5.0D0 * Q( II,J,K,L,...

...y I want to create a probability matrix to be used in a trinomial tree going forward. This is the reason why I thought to build the matrix around 0 would be much more efficient. I need to loop through because the probabilities will depend on my node and is not always the same per row (e.g. if N> jmax, jmax being defined in another function) I found a workaround. Please see below. Thereafter I want to optimize this function. Hopefully it works. Many thanks, Eric HWMProb <- function(N) { ProbUP<- function( a, j, dt) 1 / 6 + ((j ^ 2 * Mfactor(a, dt) ^ 2 + j * Mfactor(a, dt)) / 2)...

...eld so I cannot comment your approach. I wanted only to point out that building matrix your way is like scratching your left ear with right hand, especially in R. What if you want increase size of your matrix? E.g. you use function ProbUP once for row "0" and than for rows different from jmax (if I correctly understand your code). Use of any function depends on two parameters (row and column, let them call u and v) > ProbUP<- function( a, j, dt) 1 / 6 + ((j ^ 2 * Mfactor(a, dt) ^ 2 + j * Mfactor(a, > dt)) / 2) ######### Probability X going up > ProbMID<- fun...

Duncan, Do a quick check here on x86_64-apple-darwin10 with svn llvm and svn dragon-egg against release gcc 4.5.0, the results from the himenoBMTxpa benchmark compiled at -O3 look pretty good. With stock gcc-4.5.0, we get... Grid-size = M mimax = 128 mjmax = 128 mkmax = 256 imax = 127 jmax = 127 kmax =255 Start rehearsal measurement process. Measure the performance in 3 times. MFLOPS: 156.560865 time(s): 2.575476 1.733593e-03 Now, start the actual measurement process. The loop will be excuted in 69 times This will take about one minute. Wait...

Hi Peter, > Why not do this too? I've applied this - thanks for the patch! Ciao, Duncan.

...ironment and then run the loop with the iF statement, as per below. for (j in 0:2) { if (j==0) { prb["0","1"] <- ProbUP(a,j,dt) prb["0","0"] <- ProbMID(a,j,dt) prb["0","-1"] <- ProbDWN(a,j,dt) } else { if (j==jmax) { prb[paste(j,sep = ""),"1"] <- TOPProbUP(a,j,dt) prb[paste(j,sep = ""),"0"] <- TOPProbMID(a,j,dt) prb[paste(j,sep = ""),"-1"] <- TOPProbDWN(a,j,dt) prb[paste(-j,sep = ""),"1"] <- BT...

...iF statement, as per below. > for (j in 0:2) { > if (j==0) { > prb["0","1"] <- ProbUP(a,j,dt) > prb["0","0"] <- ProbMID(a,j,dt) > prb["0","-1"] <- ProbDWN(a,j,dt) > } > else { > if (j==jmax) { > prb[paste(j,sep = ""),"1"] <- TOPProbUP(a,j,dt) > prb[paste(j,sep = ""),"0"] <- TOPProbMID(a,j,dt) > prb[paste(j,sep = ""),"-1"] <- TOPProbDWN(a,j,dt) > prb[paste(-j,sep = ""),&qu...

Hallo, i am evaluating the possibility of using llvm for an application, and i wondering if this is the right place where to pose questions. I haven't found a llvm users mailing list ... Maurizio De Cecco

...velopers with the right skills and enough interest are found I'll set up a project mailing list to further discuss the subject. Cordially, Maurizio __________ Maurizio De Cecco - Music: http://www.myspace.com/mauriziodececco Blog: http://maurizio.dececco.name/ Software: http://www.jmax-phoenix.org/

Yeah, this is the right place, just ask :) On Tue, Jan 26, 2010 at 4:12 PM, Maurizio De Cecco <jmax at dececco.name> wrote: > Hallo, > > i am evaluating the possibility of using llvm for an application, > and i wondering if this is the right place where to pose questions. > I haven't found a llvm users mailing list ... > > Maurizio De Cecco

On Mon, Dec 6, 2010 at 6:10 AM, Maurizio De Cecco <jmax at dececco.name> wrote: > I have been looking for a while to  LLVM as a possible technology to build a > DSP execution engine, providing the runtime flexibility needed by real-time > interactive DSP applications (like patcher languages), or by plug-in based > processors, and in the s...

Hi, and thanks for the feedback. >My own gut feeling on this is that you'd be better off figuring out >how to do this in the context of Faust, which already does a important >subset of what you are describing, though notably without (I think) >the LLVM part. Surely a contribution to the discussion by the Faust people would be welcome; and even more than to the discussion :->.