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COMBI improvements

COMBI improvements. Claudia Tambasco, Tatiana Pieloni, Xavier Buffat , Danilo Banfi. Beam-Beam meeting– 17 th April 2014. Contents. Bug in COMBI found Correction for ion simulations (soft Gaussian) New features for the BTF routine Conclusions and ongoing work.

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COMBI improvements

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  1. COMBI improvements Claudia Tambasco, Tatiana Pieloni, Xavier Buffat, DaniloBanfi Beam-Beam meeting– 17th April 2014

  2. Contents • Bug in COMBI found • Correction for ion simulations (soft Gaussian) • New features for the BTF routine • Conclusions and ongoing work Claudia Tambasco, Beam-Beam meeting– 17th April 2014

  3. Bug fno-automatic command • The fno-automatic command in the Makefile was added to avoid this complaint writing a debuging file for the HFMM: ‪At line 137 of file src/fortran/fmmprin.F (unit = 5, file = 'stdin')‬ ‪Fortran runtime error: Cannot write to file opened for READ‬ Running simulations with the HFMM and OpenMpi an intensity increment was affecting the simulations Further investigations have shown that this problem was related to the fno-automatic command • Is there an incompatibility between OpenMpi and that command? Claudia Tambasco, Beam-Beam meeting– 17th April 2014

  4. Correction for ion simulations(soft Gaussian approx) • To perform simulations for beam-beam interaction studies at RHIC with soft Gaussian approximation Modified formula for the calculation of the particle radius in order to take into account the charge of the other beam Input file: the ion intensity must to be expressed as the number of ions per bunch 1IP (2 bunches) Fractional tunes: 0.22-0.23 From SL/Note 95-33(AP) EberardKeil: Au ions A2 mass of the ion in proton mass units Au ions (charge 79) Analytical π mode frequency: 0.2162 Yokoya factor (soft Gaussian): 1.1 Claudia Tambasco, Beam-Beam meeting– 17th April 2014

  5. New features for the BTF routine • Modified the previous BTF routine, by passing arguments to the action is possible: • To select the initial and final frequency • To choose after many turns the BTF excitation starts • To choose the number of turns for each step of the BTF • To define the resolution Claudia Tambasco, Beam-Beam meeting– 17th April 2014

  6. Conclusions • To use OpenMpi and HFMM the fno-automatic command must be removed from the make file • Now is possible to run ion simulations by using the Gaussian approximation HFMM case under investigation! • New BTF routine to study frequency spectra response under sinusoidal excitation Ongoing work: • BTF response studies in case of RHIC • e-lens implementation in COMBI code to analyze RHIC data • COMBI documetation Claudia Tambasco, Beam-Beam meeting– 17th April 2014

  7. Backup

  8. -fno-automatic ‪When you switch OpenMP support on, no automatic static allocation is used and your dense arrays gets allocated on the stack of the routine. The default stack limits on OS X are very restrictive, hence the segmentation fault.‬ ‪-fno-automatic‬ ‪(This option specifies that all local variables and arrays are to be treated as if they were named in ‬`SAVE'‪ statements.) Many other compilers do this automatically, which means lots of Fortran code developed with those compilers depends on it. The effect of this is that all variables and arrays are made static, that is, not placed on the stack or in heap storage. This might cause a buggy program to appear to work better. If so, rather than relying on this command-line option (and hoping all compilers provide the equivalent one), add ‬`SAVE'‪ statements to some or all program unit sources, as appropriate. Consider using ‬`-Wuninitialized'‪ (which requires ‬`-O'‪) to find likely candidates, but do not specify ‬`-finit-local-zero'‪ or ‬`-fno-automatic'‪, or this technique won't work. The default is ‬`-fautomatic'‪, which tells ‬g77‪ to try and put variables and arrays on the stack (or in fast registers) where possible and reasonable. This tends to make programs faster.‬ Claudia Tambasco, Beam-Beam meeting– 17th April 2014

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