performance topic: SpringDamperPtP

[johhell]

I tried to run a Modia3D model several times and found differences in simulation time

test 1: using explicit functions for spring and damping

Instantiating model tetherTest
  in module: Main.T7
  in file: /home/hans/Projekte/OM/lib--------------
  0.273864 seconds (401.92 k allocations: 16.911 MiB, 64.15% compilation time)
  0.097515 seconds (329.34 k allocations: 12.203 MiB)
  0.123545 seconds (329.34 k allocations: 12.203 MiB, 16.86% gc time)
  0.097040 seconds (329.34 k allocations: 12.203 MiB)
  0.097082 seconds (329.34 k allocations: 12.203 MiB)
  0.096970 seconds (329.34 k allocations: 12.203 MiB)
Main.T7

test 2: using parameters for spring and damping

takes longer, due to additional compilation time for eval()

Instantiating model tetherTest
  in module: Main.T7
  in file: /home/hans/Projekte/OM/lib--------------
  0.287922 seconds (370.37 k allocations: 16.131 MiB, 64.70% compilation time)
  0.157830 seconds (309.42 k allocations: 12.206 MiB, 14.23% gc time, 17.60% compilation time)
  0.128409 seconds (309.40 k allocations: 12.204 MiB, 21.92% compilation time)
  0.129223 seconds (309.40 k allocations: 12.204 MiB, 21.82% compilation time)
  0.131308 seconds (309.40 k allocations: 12.204 MiB, 21.95% compilation time)
  0.129613 seconds (309.40 k allocations: 12.204 MiB, 21.62% compilation time)
Main.T7

test 3: using parameters for spring and damping with modified SpringDamperPtP.jl

Instantiating model tetherTest
  in module: Main.T7
  in file: /home/hans/Projekte/OM/lib--------------
  0.259682 seconds (364.23 k allocations: 15.735 MiB, 61.97% compilation time)
  0.099671 seconds (303.25 k allocations: 11.807 MiB)
  0.097721 seconds (303.25 k allocations: 11.807 MiB)
  0.098235 seconds (303.25 k allocations: 11.807 MiB)
  0.122374 seconds (303.25 k allocations: 11.807 MiB, 14.12% gc time)
  0.097432 seconds (303.25 k allocations: 11.807 MiB)
Main.T7

a PR will be opened soon. It works, but I'm not the expert - check it carefully. Danke.
code sniplet below:

        if (!isa(springForceLaw, Function))
            stiffness = Modia3D.convertAndStripUnit(F, u"N/m", springForceLaw)
            fkt1(_x) = stiffness*_x
        else
            fkt1 = springForceLaw
        end

[johhell]

an additional MWE (without Modia3D)

module T1

mutable struct SpringDamperPtP
    path::String
    springForceFunction::Function
    damperForceFunction::Function

    function SpringDamperPtP(; path::String = "",
                                  springForceLaw::Union{Real, Function} = 0.0,
                                  damperForceLaw::Union{Real, Function} = 0.0 )

        if (!isa(springForceLaw, Function))
#             stiffness = Modia3D.convertAndStripUnit(F, u"N/m", springForceLaw)
            stiffness = springForceLaw
            fkt1(_x) = stiffness*_x
        else
            fkt1 = springForceLaw
        end

        if (!isa(damperForceLaw, Function))
#             damping = Modia3D.convertAndStripUnit(F, u"N*s/m", damperForceLaw)
            damping = damperForceLaw
            fkt2(_x) = damping*_x
        else
            fkt2 = damperForceLaw
        end

        return new(path, fkt1, fkt2)
    end
end


function evaluateForceElement(force::SpringDamperPtP, )
    pos = 100.0
    vel = 10.0
    fc = force.springForceFunction(pos)
    fd = force.damperForceFunction(vel)

    println("$(force.path)   fc = $(fc)    fd = $(fd)")
    println()

    nothing
end


fc(x) = 100.0*x
fd(x) = 1.111*x

A = SpringDamperPtP(;path="function + function     ", springForceLaw=fc, damperForceLaw=fd)
B = SpringDamperPtP(;path="parameter + parameter   ", springForceLaw=33.0, damperForceLaw=0.999)
C = SpringDamperPtP(;path="function + parameter    ", springForceLaw=fc, damperForceLaw=0.999)
D = SpringDamperPtP(;path="parameter + function    ", springForceLaw=33.0, damperForceLaw=fd)
evaluateForceElement(A)
evaluateForceElement(B)
evaluateForceElement(C)
evaluateForceElement(D)

end

[GerhardHippmann]

Fixed by #133

[johhell]

the same code block (with eval(...) ) is in included in Bushing.jl. Should be updated as well.
Thanks.