Tim Wescott <seemywebsite@myfooter.really> wrote:>On Thu, 21 Jul 2016 00:17:30 +0000, Steve Pope wrote:>> Tim Wescott <seemywebsite@myfooter.really> wrote:>>> I'm trying to decide how hard I need to push, early on, for the >>> computationally intensive bits to be done in C++.>> I would say, not at all, unless you think your failure to steer them on >> the issue might cause the project to collapse and negatively impact your >> future revenues; but even in this scenario you do not want to directly >> challenge their internal technical approach.>My job is to point them in the direction of success. If that means that >using the computing language they're comfortable with won't lead to >success, then I need to point that out to them -- even if they don't like >it. I won't beat them with a stick, but they need to understand.>> I would recommend proposing to include a C++ program among your >> deliverables to them, so that they have a reference implementation. You >> may also want to propose a certain number of your hours as post-delivery >> support.>They specifically don't want to pay for that -- there will be a Scilab >program, but that has run-times roughly comparable to Labview.I have run into analogous situations where the customr wants me to deliver an algorithm, but does not want even sample code as this means (in their thinking) that they are paying for coding it twice. So all they get is a paper design. (Even though I have coded it up anyway.) The customer is always right. :-) Steve
Labview vs. C++
Started by ●July 20, 2016
Reply by ●July 21, 20162016-07-21
Reply by ●July 21, 20162016-07-21
Tim Wescott <seemywebsite@myfooter.really> writes:>> proposing to include a C++ program > They specifically don't want to pay for that -- there will be a Scilab > program, but that has run-times roughly comparable to Labview.I wonder if you could estimate without too much effort how much calculation is required, and then ask the customer to run a simple benchmark in Labview that calculates about that much, to see whether it can keep up.
Reply by ●July 21, 20162016-07-21
On Thursday, July 21, 2016 at 10:55:09 AM UTC-7, Tim Wescott wrote:> On Thu, 21 Jul 2016 05:45:43 -0700, makolber wrote:(snip)> > You write the critical C part and provide documentation and they do the > > overall Labview.> Yes, but this time _they_ want to write all of it (for tax reasons -- it > doesn't have to make sense if it's for tax reasons).OK, but the solution also doesn't have to make sense, for tax reasons. There is a story from some years ago (might have changed) that the tax rate on pick-up truck assembled in Japan and US was different. Japanese pick-up truck makers would build chassis and bodies in Japan, ship them to the US, put the bodies on the chassis, and they were now US assembled. No matter that 99% of the assembling was in Japan. The tax rules for software might be different, but it might be that you can send a C function, and sample LabView code for calling C, and the customer writes the actual LabView to C call for tax purposes. Tax laws could be completely different, but with a tax lawyer you might find the right solution. Or you might, for example, write the algorithm in Java with a sample to call the Java static method. An appropriately written Java static method should translate to C relatively directly, yet for legal purposes, even more than the case above, the C code is newly written. (It seems to me that in many ways Java is more C like than C++ is C like. I believe that was intentional.)
Reply by ●July 21, 20162016-07-21
On Thu, 21 Jul 2016 12:30:49 -0500, Tim Wescott <seemywebsite@myfooter.really> wrote:>On Thu, 21 Jul 2016 00:17:30 +0000, Steve Pope wrote: > >> Tim Wescott <seemywebsite@myfooter.really> wrote: >> >>> Problem: I'm working on a proposal for a customer, for an app that's >>> going to require heavy computation and is more or less real time*. The >>> guy I'll be working with the closest is pretty much a 100% LabView >>> programmer -- he just doesn't _do_ C, or C++, or Fortran. >> >>> The customer wants me to deliver them an algorithm, to which they'll >>> write code. They're pretty firm (for good reason) on wanting to do the >>> code in-house, or with local talent. >> >> Sounds good >> >>> I'm trying to decide how hard I need to push, early on, for the >>> computationally intensive bits to be done in C++. >> >> I would say, not at all, unless you think your failure to steer them on >> the issue might cause the project to collapse and negatively impact your >> future revenues; but even in this scenario you do not want to directly >> challenge their internal technical approach. > >My job is to point them in the direction of success. If that means that >using the computing language they're comfortable with won't lead to >success, then I need to point that out to them -- even if they don't like >it. I won't beat them with a stick, but they need to understand.I think that's all you can do, that is, make a recommendation. Sometimes you can write parts of it in red ink, with big arrows pointing at it, but that's really all you can do. If the client doesn't want more than that, then that's where you stop. I've had to do that on a number of occasions, where you kinda knew things were ultimately gonna go badly, but you did your part as requested. It's never fun or easy. Sometimes you get to charge extra to come back and clean things up later. ;)>> I would recommend proposing to include a C++ program among your >> deliverables to them, so that they have a reference implementation. You >> may also want to propose a certain number of your hours as post-delivery >> support. > >They specifically don't want to pay for that -- there will be a Scilab >program, but that has run-times roughly comparable to Labview.I think that's a good place to leave it, in other words, provide a well-documented algorithm with lots of stated caveats about execution time and latency in the feedback paths, and leave it at that.
Reply by ●July 21, 20162016-07-21
On Thu, 21 Jul 2016 12:13:19 -0700, Paul Rubin wrote:> Tim Wescott <seemywebsite@myfooter.really> writes: >>> proposing to include a C++ program >> They specifically don't want to pay for that -- there will be a Scilab >> program, but that has run-times roughly comparable to Labview. > > I wonder if you could estimate without too much effort how much > calculation is required, and then ask the customer to run a simple > benchmark in Labview that calculates about that much, to see whether it > can keep up.I plan on doing that at any rate. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com I'm looking for work -- see my website!
Reply by ●July 21, 20162016-07-21
On Thu, 21 Jul 2016 13:22:05 -0700, herrmannsfeldt wrote:> On Thursday, July 21, 2016 at 10:55:09 AM UTC-7, Tim Wescott wrote: >> On Thu, 21 Jul 2016 05:45:43 -0700, makolber wrote: > > (snip) >> > You write the critical C part and provide documentation and they do >> > the overall Labview. > >> Yes, but this time _they_ want to write all of it (for tax reasons -- >> it doesn't have to make sense if it's for tax reasons). > > OK, but the solution also doesn't have to make sense, for tax reasons. > > There is a story from some years ago (might have changed) that the tax > rate on pick-up truck assembled in Japan and US was different. > > Japanese pick-up truck makers would build chassis and bodies in Japan, > ship them to the US, put the bodies on the chassis, and they were now US > assembled. No matter that 99% of the assembling was in Japan. > > The tax rules for software might be different, but it might be that you > can send a C function, and sample LabView code for calling C, > and the customer writes the actual LabView to C call for tax purposes. > > Tax laws could be completely different, but with a tax lawyer you might > find the right solution. > > Or you might, for example, write the algorithm in Java with a sample to > call the Java static method. An appropriately written Java static > method should translate to C relatively directly, yet for legal > purposes, even more than the case above, the C code is newly written. > > (It seems to me that in many ways Java is more C like than C++ is C > like. I believe that was intentional.)I really don't mind just delivering an algorithm, and I've had good success with doing that on two or three occasions. Basically, there's people out there who have a flair for propping a scientific paper next to their 'puter screen and churning out code to make it real, even if they could never come up with the math themselves. If they can find one, they'll do just fine. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com I'm looking for work -- see my website!
Reply by ●July 21, 20162016-07-21
On Thu, 21 Jul 2016 16:54:15 -0500, Tim Wescott <seemywebsite@myfooter.really> wrote:>On Thu, 21 Jul 2016 13:22:05 -0700, herrmannsfeldt wrote: > >> On Thursday, July 21, 2016 at 10:55:09 AM UTC-7, Tim Wescott wrote: >>> On Thu, 21 Jul 2016 05:45:43 -0700, makolber wrote: >> >> (snip) >>> > You write the critical C part and provide documentation and they do >>> > the overall Labview. >> >>> Yes, but this time _they_ want to write all of it (for tax reasons -- >>> it doesn't have to make sense if it's for tax reasons). >> >> OK, but the solution also doesn't have to make sense, for tax reasons. >> >> There is a story from some years ago (might have changed) that the tax >> rate on pick-up truck assembled in Japan and US was different. >> >> Japanese pick-up truck makers would build chassis and bodies in Japan, >> ship them to the US, put the bodies on the chassis, and they were now US >> assembled. No matter that 99% of the assembling was in Japan. >> >> The tax rules for software might be different, but it might be that you >> can send a C function, and sample LabView code for calling C, >> and the customer writes the actual LabView to C call for tax purposes. >> >> Tax laws could be completely different, but with a tax lawyer you might >> find the right solution. >> >> Or you might, for example, write the algorithm in Java with a sample to >> call the Java static method. An appropriately written Java static >> method should translate to C relatively directly, yet for legal >> purposes, even more than the case above, the C code is newly written. >> >> (It seems to me that in many ways Java is more C like than C++ is C >> like. I believe that was intentional.) > >I really don't mind just delivering an algorithm, and I've had good >success with doing that on two or three occasions. Basically, there's >people out there who have a flair for propping a scientific paper next to >their 'puter screen and churning out code to make it real, even if they >could never come up with the math themselves. > >If they can find one, they'll do just fine. >I've been that guy many times. ;)
Reply by ●July 21, 20162016-07-21
On Thursday, July 21, 2016 at 2:54:23 PM UTC-7, Tim Wescott wrote: (snip on algorithms, distribution, and implemention)> I really don't mind just delivering an algorithm, and I've had good > success with doing that on two or three occasions. Basically, there's > people out there who have a flair for propping a scientific paper next to > their 'puter screen and churning out code to make it real, even if they > could never come up with the math themselves.Some time ago, I wrote a JBIG2 compressor from the description. It took some time to get right, and the result of mistakes can be interesting. Adobe reader has had the decompressor for some years now, so I could write PDFs and test them that way. With a small enough mistake, it will work for a while, until a rare data combination occurs, after which it produces pretty much random bits. First I got it to properly compress all zero (white) input. Then all black input. Then progressively more complicated input. The last bug I had to fix only occurred when the input data width isn't a multiple of eight. (That is, not an integer number of bytes wide.) With 400dpi data, it was fairly easy to generate multiple of eight, but sometime later I didn't do that. If there is an easy test for correctness, then it should be fine to distribute the description only. Otherwise, you need a way to verify the implementation. -- glen
Reply by ●July 22, 20162016-07-22
On Thursday, July 21, 2016 at 11:57:07 AM UTC+12, Tim Wescott wrote:> OK. Neither of the groups to which I'm cross-posting this are > appropriate. > > But, y'all are smart, and I know who to listen to. > > Problem: I'm working on a proposal for a customer, for an app that's > going to require heavy computation and is more or less real time*. The > guy I'll be working with the closest is pretty much a 100% LabView > programmer -- he just doesn't _do_ C, or C++, or Fortran. > > The customer wants me to deliver them an algorithm, to which they'll > write code. They're pretty firm (for good reason) on wanting to do the > code in-house, or with local talent. I'm trying to decide how hard I > need to push, early on, for the computationally intensive bits to be done > in C++. > > I just Googled, and didn't find any good references on the relative > speeds of doing things in some compiled language vs. Labview. If the > ratio is similar to what you get in Scilab or Matlab, then they need to > go with C++. > > So -- anyone know? Any comments? > > Thanks. > > * It's not 100% hard real time, with an "exceed and you die" sort of > deadline, but after the nominal deadline the slope of the user-crankiness > vs. delay curve is pretty steep. Moreover, while _occasional_ delays > could be tolerated, if the computer just can't keep up then the delays > will grow ever longer -- and the user ever crankier -- with time. > > -- > > Tim Wescott > Wescott Design Services > http://www.wescottdesign.com > > I'm looking for work -- see my website!LabView runs about the same speed as C++. When you press the run button it compiles into the native code of the computer. A great way to write code. However, you are better using a compact Rio or single board Rio if he wants real-time because a PC is non-deterministic. You need a real-time OS and a Rio gives you this and FPGA for the front end.
Reply by ●July 23, 20162016-07-23
On Fri, 22 Jul 2016 18:34:08 -0700, gyansorova wrote:> On Thursday, July 21, 2016 at 11:57:07 AM UTC+12, Tim Wescott wrote: >> OK. Neither of the groups to which I'm cross-posting this are >> appropriate. >> >> But, y'all are smart, and I know who to listen to. >> >> Problem: I'm working on a proposal for a customer, for an app that's >> going to require heavy computation and is more or less real time*. The >> guy I'll be working with the closest is pretty much a 100% LabView >> programmer -- he just doesn't _do_ C, or C++, or Fortran. >> >> The customer wants me to deliver them an algorithm, to which they'll >> write code. They're pretty firm (for good reason) on wanting to do the >> code in-house, or with local talent. I'm trying to decide how hard I >> need to push, early on, for the computationally intensive bits to be >> done in C++. >> >> I just Googled, and didn't find any good references on the relative >> speeds of doing things in some compiled language vs. Labview. If the >> ratio is similar to what you get in Scilab or Matlab, then they need to >> go with C++. >> >> So -- anyone know? Any comments? >> >> Thanks. >> >> * It's not 100% hard real time, with an "exceed and you die" sort of >> deadline, but after the nominal deadline the slope of the >> user-crankiness vs. delay curve is pretty steep. Moreover, while >> _occasional_ delays could be tolerated, if the computer just can't keep >> up then the delays will grow ever longer -- and the user ever crankier >> -- with time. >> >> -- >> >> Tim Wescott Wescott Design Services http://www.wescottdesign.com >> >> I'm looking for work -- see my website! > > LabView runs about the same speed as C++. When you press the run button > it compiles into the native code of the computer. A great way to write > code. > However, you are better using a compact Rio or single board Rio if he > wants real-time because a PC is non-deterministic. You need a real-time > OS and a Rio gives you this and FPGA for the front end.It's real time in the "tons-o-math to be done in seconds" sense, rather than "hit the nail on the head within a millisecond" sense. We've got a previous version that's working fine. Thanks for the comment on speed. I may still want to do benchmarks, but it sounds like I don't need to worry much, if at all. -- Tim Wescott Control systems, embedded software and circuit design I'm looking for work! See my website if you're interested http://www.wescottdesign.com
