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Topic: Possible issue in using 80 bit variables. (Read 623 times) |
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Edja
Developer
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Posts: 60
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Re: Possible issue in using 80 bit variables.
« Reply #4 on: Mar 25th, 2015, 11:48pm » |
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Quote:| Clearly an issue if the program is to be run in both versions? |
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Does this have to be an issue? In what circumstances would a program have to run in two versions? I think two possibilities cover 99.9% of the cases :
The program is for your personal usage. Then choose your version 5.95a or 6.00a and stick with it.The program is for a number of users and they may not be alligned on one version (they may even have no BB4W on their PC's). Again, choose one version. This time compile the program, then distribute it. They will all see the same result. You are completely in control.
Quote:| I am working on some tools and libraries in some of my spare time, and i want them to function equally in v5 and v6 |
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But maybe you want to migrate an existing program from v5.95a to v6.00a. Or you want to use a library you've developed earlier in 5.95a and INSTALL it in a new program with v6.00a. In this case you may have a point. Still I wonder why you would want this ?
But I think Richard has documented the possible caveats and the way to avoid any problems in such case.
Eddy
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sveinioslo
Developer
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Posts: 64
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Re: Possible issue in using 80 bit variables.
« Reply #5 on: Mar 26th, 2015, 09:17am » |
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Ok, think i know my issue here, all my projects was started in v5, they are stored in a web folder so that i can work on them from different computers. Two have only v5 installed and two have both, and in the ones with both versions installed, v6 is opened by default.
Easily fixed, my lack of understanding the floating point math, is another matter.
I have some reading to do.!
Thank you, Richard and Eddy for putting me straight.
Svein
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rtr2
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Re: Possible issue in using 80 bit variables.
« Reply #6 on: Mar 26th, 2015, 10:02am » |
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on Mar 25th, 2015, 11:48pm, Edja wrote:| Or you want to use a library you've developed earlier in 5.95a and INSTALL it in a new program with v6.00a. |
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v5.95a and v6.00a share libraries (at least, if they are installed in the default location) and the supplied 'standard' libraries are fully compatible with both versions - with the exception of the undocumented PROC_transpose$() in ARRAYLIB, now hopefully fixed in the version recently uploaded to the group. Indeed v6.00a comes with a couple of updated libraries which are of benefit to v5.95a also.
So it would be highly desirable if user-generated libraries were also compatible with both v5 and v6. I would not expect that to be at all onerous: the vast majority of BBC BASIC programs (I would guess in excess of 99%) require no modification to run perfectly well in v6.00a, and there is no reason why libraries - at least not the sort likely to be written by users - should be any different.
I do not even class Svein's issue as being a 'true' incompatibility between v5 and v6. Rather it is an issue of the program being unduly sensitive to infinitesimal differences in numeric value, which is a characteristic that is worth fixing even if the intention is to run it only in one version.
Richard.
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