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Switching to modern and modular precision declaration #42

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sbryngelson opened this issue Nov 27, 2022 · 1 comment · May be fixed by #119
Open

Switching to modern and modular precision declaration #42

sbryngelson opened this issue Nov 27, 2022 · 1 comment · May be fixed by #119
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@wilfonba
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enhancement New feature or request good first issue Good for newcomers help wanted Extra attention is needed

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@sbryngelson
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MFC is filled with lines like this:

MFC/src/simulation/m_hypoelastic.f90

Lines 30 to 32 in a39962c

real(kind(0d0)), allocatable, dimension(:, :, :) :: du_dx, du_dy, du_dz
real(kind(0d0)), allocatable, dimension(:, :, :) :: dv_dx, dv_dy, dv_dz
real(kind(0d0)), allocatable, dimension(:, :, :) :: dw_dx, dw_dy, dw_dz

where the precision is declared via kind(0d0).
We also have a ton of this

MFC/src/simulation/m_riemann_solvers.fpp

Lines 547 to 556 in a39962c

rho_L = 0d0
gamma_L = 0d0
pi_inf_L = 0d0
rho_R = 0d0
gamma_R = 0d0
pi_inf_R = 0d0
alpha_L_sum = 0d0
alpha_R_sum = 0d0

where inline constants have precision declared in a "hard-coded" way.

What is better is declaring a separate constant that we can change as needed, like this
example, though there are many others.

A fix for this issue would remove all cases of 0d0 and kind(0d0) and replace them with a constant declared in the common/ directory. I think this is a suitable task for @anshgupta1234 .

I realize one can force precision via compiler variables, but I believe we should avoid this because there is an established language standard.
@sbryngelson sbryngelson added the enhancement New feature or request label Nov 27, 2022
@sbryngelson
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sbryngelson commented Feb 4, 2023 •
edited

note this from the miniweather app:

https://github.com/mrnorman/miniWeather/blob/9869dcffb19c4b07bc88f2b8adf98ca9e95bb997/fortran/miniWeather_mpi_openacc.F90#L13-L20

an important thing to notice is that if one switches to single precision, you have to switch the MPI kind as well (notice all the MPI_DOUBLE_PRECISION business in m_mpi_proxy.f90).

Update: We would probably only update the precision for a few variables, so it seems rather unlikely to touch m_mpi_proxy or MPI types.

@belericant belericant linked a pull request Mar 10, 2023 that will close this issue
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@henryleberre henryleberre linked a pull request Mar 11, 2023 that will close this issue
Add Modular fp #119
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@sbryngelson sbryngelson assigned wilfonba and unassigned belericant May 8, 2023
@sbryngelson sbryngelson added help wanted Extra attention is needed good first issue Good for newcomers labels May 22, 2024
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@wilfonba wilfonba

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enhancement New feature or request good first issue Good for newcomers help wanted Extra attention is needed
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Add Modular fp belericant/MFC
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@belericant @henryleberre @anshgupta1234 @sbryngelson @wilfonba