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Re: Is FORTRAN a dying language?
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| John Lansberry wrote:
>
> I'm wondering if you would be so kind as to supply some details of this
> disaster. C++ is the flavor of the day (OK, past few years) where I work,
> and I find it's supposed benefits to be completely unconvincing.
Here's a particularly memorable case. It should make you cringe how our
taxes finance the holy warriors and their newly minted hoes...
> In 1996, an enlightened manager decided that the maintenance costs could
> be reduced if the whole thing were re-written in C++. The estimate to
> finish the project was 120 work years. If rewriting it could reduce the
> maintenance cost to zero work years per year, the project would have broken
> even in 2023 -- assuming the new program still gets the right answers. So
> far, 140+ work years have been expended, and the estimated cost to complete
> the project is still 120 work years. One guy was given the job of re-writing
> the integrator for the initial-value problem for ordinary differential
> equations. These 2200 or so lines of Fortran 77 tackle the central problem
> of orbit determination: Solving Newton's equations of motion. This package
> is not a simple RKF45 integrator from Numerical Recipes. It's a variable-
> order variable-step Adams-Moulton integrator that solves second-order
> equations directly. The sophisitication is well justified, but that's a
> story for another day. After two years, he hadn't even finished the
> interface! This guy is not a lazy idiot, or completely unfamiliar with
> C++. He had previously completed several other projects in C++ successfully.
> The problem wasn't the engineer; the problem was that C++ is not the right
> tool for this job.
> -- Van Snyder (JPL)
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| Gerry Thomas 2004-05-12, 9:09 pm |
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"bv" <bvoh@Xsdynamix.com> wrote in message
news:40A03CA6.A8A6D86C@Xsdynamix.com...
> John Lansberry wrote:
work,[color=darkred]
>
> Here's a particularly memorable case. It should make you cringe how our
> taxes finance the holy warriors and their newly minted hoes...
>
could[color=darkred]
the[color=darkred]
broken[color=darkred]
So[color=darkred]
complete[color=darkred]
re-writing[color=darkred]
problem[color=darkred]
package[color=darkred]
variable-[color=darkred]
a[color=darkred]
successfully.[color=darkred]
right[color=darkred]
>
The only thing memorable about Van Snyder's anecdote was his shirking
failure to explain why Hindmarsh's (LLNL) VODE in C from Netlib or the ODE
solver in MATLAB (compiled to a C/C++ standalone) weren't considered or
perhaps they were but you'll never know. This would have taken a wet
afternoon to do but when you can budget for a crew and craft per decade,
who's counting? One wonders if the crackerjack C programmer referred to was
the one and only Robert E. Tisdale, who presents as spokesman for JILA,
NASA, Van Snyder, etc. on matters Fortran/C. Is governance at NASA a joke
while F77 reigns, C/C++ is elbowing in, and F3K is in the planning?
--
E&OE
Ciao,
Gerry T.
______
"There's man all over for you, blaming on his boots the fault of his
feet." -- Samuel Beckett.
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| Dr Chaos 2004-05-12, 9:09 pm |
| On Tue, 11 May 2004 00:08:04 -0400, Gerry Thomas <gfthomas@sympatico.ca> wrote:
>
> The only thing memorable about Van Snyder's anecdote was his shirking
> failure to explain why Hindmarsh's (LLNL) VODE in C from Netlib or the ODE
> solver in MATLAB (compiled to a C/C++ standalone) weren't considered or
> perhaps they were but you'll never know.
I'm not the original poster but there is no need to be snide. I
can guess at the issue.
The key point you missed was solving "second order equations directly",
namely Newtonian mechanics.
MATLAB??? and what happens when the MATLAB algorithm changes?
> This would have taken a wet
> afternoon to do but when you can budget for a crew and craft per decade,
> who's counting? One wonders if the crackerjack C programmer referred to was
> the one and only Robert E. Tisdale, who presents as spokesman for JILA,
> NASA, Van Snyder, etc. on matters Fortran/C. Is governance at NASA a joke
> while F77 reigns, C/C++ is elbowing in, and F3K is in the planning?
It's generally considered a good idea to conserve conserved quantities
in celestial mechanics, especially when multimillion dollar spacecraft
are at risk.
Sometimes off-the-shelf packages give you off-the-shelf solutions.
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| Gerry Thomas 2004-05-12, 9:09 pm |
|
"Dr Chaos" <mbkennelSPAMBEGONE@NOSPAMyahoo.com> wrote in message
news:slrnca24jc.7n0.mbkennelSPAMBEGONE@lyapunov.ucsd.edu...
> On Tue, 11 May 2004 00:08:04 -0400, Gerry Thomas <gfthomas@sympatico.ca>
wrote:
ODE[color=darkred]
>
> I'm not the original poster but there is no need to be snide. I
> can guess at the issue.
>
> The key point you missed was solving "second order equations directly",
> namely Newtonian mechanics.
Second order equations can be cast as a pair of coupled first order
equations to which VODE and MATLAB apply.
>
> MATLAB??? and what happens when the MATLAB algorithm changes?
>
It's been years since Shampine's MATLAB ODE Suite changed and if it does
then recompile.
decade,[color=darkred]
was[color=darkred]
joke[color=darkred]
>
> It's generally considered a good idea to conserve conserved quantities
> in celestial mechanics, especially when multimillion dollar spacecraft
> are at risk.
>
?
> Sometimes off-the-shelf packages give you off-the-shelf solutions.
>
Shampine's off-the-shelf package is highly regarded, unlike JILA's it would
seem.
--
E&OE
Ciao,
Gerry T.
______
"A cynic is one who knows the price of everything and the value of
nothing." -- Oscar Wilde.
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| Dr Chaos 2004-05-12, 9:09 pm |
| On Tue, 11 May 2004 14:21:32 -0400, Gerry Thomas <gfthomas@sympatico.ca> wrote:
>
> "Dr Chaos" <mbkennelSPAMBEGONE@NOSPAMyahoo.com> wrote in message
> news:slrnca24jc.7n0.mbkennelSPAMBEGONE@lyapunov.ucsd.edu...
> wrote:
> ODE
>
> Second order equations can be cast as a pair of coupled first order
> equations to which VODE and MATLAB apply.
Yes of course, I do that all the time, and I use SLATEC and other
pre-packaged integration routines with wondeful success.
But for high-performance and high-accuracy needs, especially with
symmetries and conserved quantities, a specialized routine may be
better. I don't know about this specifics but sometimes preserving
symplectic properties (Hamiltonian structure) can be important. And
in spacecraft navigation and astronomical guidance, getting accuracy
down to the last bit is a critical need.
>
> Shampine's off-the-shelf package is highly regarded, unlike JILA's it would
> seem.
Yes, it's great. The original Fortran version of NASA's code sounded
like it was good too.
And I agree with the notion that attempting to convert to C++ was a
futile waste.
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