Daniel proposed some sort of scientific classes for D, among other
supporting library functions. What kind of functionality would that
include? Are there similar classes for other languages that would make
good examples? I'm guessing that it would contain a lot of constants,
and maybe functions for converting between units, what else? I would
like to help with something like that, but I don't really know what it
would entail.

-Jon

"Jonathan Andrew" <jon@ece.arizona.edu> escreveu na mensagem news:3E206267.70801@ece.arizona.edu...
> Daniel proposed some sort of scientific classes for D, among other supporting library functions. What kind of functionality would that include? Are there similar classes for other languages that would make good examples? I'm guessing that it would contain a lot of constants, and maybe functions for converting between units, what else? I would like to help with something like that, but I don't really know what it would entail.
>
> -Jon
>

Hi,

    I'm thinking about safe quantities (value unit pairs) for
type-preserving algebra, classes to represent vectors, vector fields,
spaces, equations, standard graphs for rendering. Lot's of stuff. I have
lots of thoughts about it (was physics major once, before quitting college
:-( and have some good background, mostly calculus and mathematics applied
to physics). IMHO we can use a simple approach to defining units. A basic
CGSUnit class, with internal variables keeping track of each dimension's
power, lots of constants and some factory methods to create specialized
units (speed, mass, etc.). If Walter add support in D templates for values,
like c++ does, we can make instance TUnit(1,0,0) length, be a different type
than instance TUnit(0,1,0) mass, with type safe algebra. Make it fast enough
and more people will start using it, at least for type-check the equations
before trying to release it using doubles. An application like
http://www.jonelo.de/java/nc/ gives me some ideas of what we need to
implement, but not how, the code is a bit ugly.
http://www.dautelle.com/jade/ provides a scientific library. I have links
for works in other languages (C++, Ada, etc.) to get a basic start of what
we need to do.

    Best regards,
    Daniel Yokomiso.

"Why should I care about posterity? What's posterity ever done for me?" - Groucho Marx


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>
>Hi,
>
>    I'm thinking about safe quantities (value unit pairs) for
>type-preserving algebra, classes to represent vectors, vector fields, spaces, equations, standard graphs for rendering. Lot's of stuff. I have lots of thoughts about it (was physics major once, before quitting college :-( and have some good background, mostly calculus and mathematics applied to physics). IMHO we can use a simple approach to defining units. A basic CGSUnit class, with internal variables keeping track of each dimension's power, lots of constants and some factory methods to create specialized units (speed, mass, etc.). If Walter add support in D templates for values, like c++ does, we can make instance TUnit(1,0,0) length, be a different type than instance TUnit(0,1,0) mass, with type safe algebra. Make it fast enough and more people will start using it, at least for type-check the equations before trying to release it using doubles. An application like http://www.jonelo.de/java/nc/ gives me some ideas of what we need to implement, but not how, the code is a bit ugly. http://www.dautelle.com/jade/ provides a scientific library. I have links for works in other languages (C++, Ada, etc.) to get a basic start of what we need to do.
>
>    Best regards,
>    Daniel Yokomiso.
>
>"Why should I care about posterity? What's posterity ever done for me?" - Groucho Marx
>
>
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>Outgoing mail is certified Virus Free.
>Checked by AVG anti-virus system (http://www.grisoft.com).
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>
>

I'll check out those links and maybe we can come up with something good. One idea I had, (if properties get implemented) is to use a property for the units of each of the quantities, and then the settor could do the appropriate conversion if you wanted to change units. Maybe in the constructor you could define the units, i.e.

mylength = new CGSUnit(10, KM);

Which would make mylength a scientific quantity of 10 kilometers. Although I must confess I don't really care for the name CGSUnit too much... maybe "Quantity" or something of that nature, but its probably too early to worry about naming schemes.

-Jon

"Jonathan Andrew" <Jonathan_member@pathlink.com> escreveu na mensagem news:avsi68$a6d$1@digitaldaemon.com...
>
> >
> >Hi,
> >
> >    I'm thinking about safe quantities (value unit pairs) for
> >type-preserving algebra, classes to represent vectors, vector fields, spaces, equations, standard graphs for rendering. Lot's of stuff. I have lots of thoughts about it (was physics major once, before quitting
college
> >:-( and have some good background, mostly calculus and mathematics
applied
> >to physics). IMHO we can use a simple approach to defining units. A basic CGSUnit class, with internal variables keeping track of each dimension's power, lots of constants and some factory methods to create specialized units (speed, mass, etc.). If Walter add support in D templates for
values,
> >like c++ does, we can make instance TUnit(1,0,0) length, be a different
type
> >than instance TUnit(0,1,0) mass, with type safe algebra. Make it fast
enough
> >and more people will start using it, at least for type-check the
equations
> >before trying to release it using doubles. An application like http://www.jonelo.de/java/nc/ gives me some ideas of what we need to implement, but not how, the code is a bit ugly. http://www.dautelle.com/jade/ provides a scientific library. I have links for works in other languages (C++, Ada, etc.) to get a basic start of
what
> >we need to do.
> >
> >    Best regards,
> >    Daniel Yokomiso.
> >
> >"Why should I care about posterity? What's posterity ever done for me?" - Groucho Marx
> >
> >
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> >Checked by AVG anti-virus system (http://www.grisoft.com).
> >Version: 6.0.435 / Virus Database: 244 - Release Date: 30/12/2002
> >
> >
>
> I'll check out those links and maybe we can come up with something good.
One
> idea I had, (if properties get implemented) is to use a property for the
units
> of each of the quantities, and then the settor could do the appropriate conversion if you wanted to change units. Maybe in the constructor you
could
> define the units, i.e.
>
> mylength = new CGSUnit(10, KM);
>
> Which would make mylength a scientific quantity of 10 kilometers. Although I must confess I don't really care for the name CGSUnit too much... maybe "Quantity" or something of that nature, but its probably too early to
worry
> about naming schemes.
>
> -Jon
>

    Well, with overloaded method names we can use scaling operations to do
the trick:


mylength = 10 * KM;


where KM has the type Length and a value of 1. This type must be able to be type safe, and AFAIK we need dimensions in some unit system to do that. SI uses seven dimensions, CGS uses 3. The tricky part is when we do something like:


mylength = 10 * KM + 123 * FEET


    With this kind of code we need to make the appropriate conversions and
keep a adequate precision. Using properties to define the kind of units
(e.g. meters vs. miles) may be better for value showing, not for the values.
Something like:


mylength = 10 * KM;
mytime = 2 * MINUTE;
myspeed = mylength / mytime;

units.time = HOUR;
units.length = FEET;
printf("%.*s\r\n", units.toString(myspeed));


    Best regards,
    Daniel Yokomiso.

"Later in this talk, I intend to define the universe and give three
examples."
- Larry Wall


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