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digitalmars.D - imaginary and complex types

reply Vegeta <lord.vegeta ica.luz.ve> writes:
I'm new to the D language and I like what I've seen so far.
But there is one thing that is wrong and it is the names of the types 
ireal  and creal.
It looks like those names mean imaginary real and complex real.
I suppose these types exist so that D is better suited to numerical
programming. But anyone who knows a little mathematics will laugh at a
language that has types with those absurd names.
Having an int real makes much more sense.

Those types should be called imaginary and complex.

Probably this discussion has happened before, but just in case.


VS
May 22 2005
next sibling parent reply "G.Vidal" <gyvidal wanadoo.fr> writes:
This is absolutely true.

I guess "real" is there to remind us the size of the variable, maybe..?

Who really needs "complex integers" anyway?
I agree those type should be renamed.
May 22 2005
parent reply Vegeta <lord.vegeta ica.luz.ve> writes:
G.Vidal wrote:


 This is absolutely true.
 
 I guess "real" is there to remind us the size of the variable, maybe..?
 


the real type has hat name because it is the largest precision floating
point type. I understand the criteria is that this type is not tied to a
particular size (e.g., double or single precision). the name real is bacuse
it describes the kind of numbers one would use with this data type.
if real does not refer to a specific size, why call the others creal and
ireal. the name should use the same criterion used to name the other type:
that is, by the type of numbers one would use with the data types. that is,
imaginary and complex.

Believe me, this alone could be a reason I wouldn't use D, especially
numerical applications. Who is going to believe that a language that
beleives in the existance of imaginary reals or complex reals is
appropriate for numerical computing?
May 22 2005
parent reply Burton Radons <burton-radons smocky.com> writes:
Vegeta wrote:


 G.Vidal wrote:
 
 

This is absolutely true.

I guess "real" is there to remind us the size of the variable, maybe..?


 
 
 the real type has hat name because it is the largest precision floating
 point type. I understand the criteria is that this type is not tied to a
 particular size (e.g., double or single precision). the name real is bacuse
 it describes the kind of numbers one would use with this data type.
 if real does not refer to a specific size, why call the others creal and
 ireal. the name should use the same criterion used to name the other type:
 that is, by the type of numbers one would use with the data types. that is,
 imaginary and complex.


Have you noticed that there are six imaginary and complex types, 
parallel to the floating-point types?  cfloat and ifloat are to float, 
cdouble and idouble are to double, creal and ireal are to real.  There's 
no deeper significance, it's purely about the precision used to 
represent the types.

"real" itself has no meaning beside that specifically defined for it 
(the greatest precision floating point type representable by the 
hardware, or double precision if no hardware support exists).  It used 
to be "extended".  This was decided to be too long and somewhat 
incorrect and was changed.  That's all there is to it.  It has nothing 
to do with either the mathematical "real" or the English word.

If you don't want to refer to complex and imaginary types like that, you 
can alias them:

    alias creal complex;
    alias ireal imaginary;
May 22 2005
parent reply "Ben Hinkle" <ben.hinkle gmail.com> writes:
"Burton Radons" <burton-radons smocky.com> wrote in message 
news:d6qrj3$2i1a$1 digitaldaemon.com...

 Vegeta wrote:


 G.Vidal wrote:



This is absolutely true.

I guess "real" is there to remind us the size of the variable, maybe..?



 the real type has hat name because it is the largest precision floating
 point type. I understand the criteria is that this type is not tied to a
 particular size (e.g., double or single precision). the name real is 
 bacuse
 it describes the kind of numbers one would use with this data type.
 if real does not refer to a specific size, why call the others creal and
 ireal. the name should use the same criterion used to name the other 
 type:
 that is, by the type of numbers one would use with the data types. that 
 is,
 imaginary and complex.


 Have you noticed that there are six imaginary and complex types, parallel 
 to the floating-point types?  cfloat and ifloat are to float, cdouble and 
 idouble are to double, creal and ireal are to real.  There's no deeper 
 significance, it's purely about the precision used to represent the types.

 "real" itself has no meaning beside that specifically defined for it (the 
 greatest precision floating point type representable by the hardware, or 
 double precision if no hardware support exists).  It used to be 
 "extended".  This was decided to be too long and somewhat incorrect and 
 was changed.  That's all there is to it.  It has nothing to do with either 
 the mathematical "real" or the English word.


It's too bad "extended" was tossed. I used that name for years as the 80-bit 
float in Apple's SANE (standard Apple numeric environment) and it never 
bothered me to type all those characters. Even the name "real" makes me 
cringe since I would expect "real" to be able to represent irrational 
numbers like sqrt(2) - eg a real number. Maybe we can call it "rat" for a 
"rational approximation to a real number". Then we'd have "rat" "irat" and 
"crat". It would give new meaning to the phrase "what is this crat?"


 If you don't want to refer to complex and imaginary types like that, you 
 can alias them:

    alias creal complex;
    alias ireal imaginary;
May 22 2005
parent reply Burton Radons <burton-radons smocky.com> writes:
Ben Hinkle wrote:

 It's too bad "extended" was tossed. I used that name for years as the 80-bit 
 float in Apple's SANE (standard Apple numeric environment) and it never 
 bothered me to type all those characters. Even the name "real" makes me 
 cringe since I would expect "real" to be able to represent irrational 
 numbers like sqrt(2) - eg a real number. Maybe we can call it "rat" for a 
 "rational approximation to a real number". Then we'd have "rat" "irat" and 
 "crat". It would give new meaning to the phrase "what is this crat?"


I agree, I liked "extended".  I'd even go so far as to prefer 
"extended_complex"; brevity should never be more important than clarity. 
  I objected to the change at the time.  But it's not like the current 
state was an irrational move made out of ignorance.  Perhaps it would 
have been better if it had been changed to something like "pont" or 
"curp"; no way to confuse it with something else then.
May 22 2005
parent reply "Ben Hinkle" <bhinkle mathworks.com> writes:
"Burton Radons" <burton-radons smocky.com> wrote in message 
news:d6qti3$2jda$1 digitaldaemon.com...

 Ben Hinkle wrote:

 It's too bad "extended" was tossed. I used that name for years as the 
 80-bit float in Apple's SANE (standard Apple numeric environment) and it 
 never bothered me to type all those characters. Even the name "real" 
 makes me cringe since I would expect "real" to be able to represent 
 irrational numbers like sqrt(2) - eg a real number. Maybe we can call it 
 "rat" for a "rational approximation to a real number". Then we'd have 
 "rat" "irat" and "crat". It would give new meaning to the phrase "what is 
 this crat?"


 I agree, I liked "extended".  I'd even go so far as to prefer 
 "extended_complex"; brevity should never be more important than clarity. I 
 objected to the change at the time.  But it's not like the current state 
 was an irrational move made out of ignorance.  Perhaps it would have been 
 better if it had been changed to something like "pont" or "curp"; no way 
 to confuse it with something else then.


I could picture either of
 float, double, real, ifloat, idouble, imaginary, cfloat, cdouble, complex
or
 float, double, extended, ifloat, idouble, iextended, cfloat, cdouble, 
cextended

The first is consistent with mathematical naming of "real", "imaginary" and 
"complex" while the second is consistent with prefixing the precision. Using 
the word "real", which is a matheamical word, to indicate precision doesn't 
seem like a workable solution.
May 23 2005
parent Dave <Dave_member pathlink.com> writes:
In article <d6ssnk$1ddn$1 digitaldaemon.com>, Ben Hinkle says...

"Burton Radons" <burton-radons smocky.com> wrote in message 
news:d6qti3$2jda$1 digitaldaemon.com...

 Ben Hinkle wrote:

 It's too bad "extended" was tossed. I used that name for years as the 
 80-bit float in Apple's SANE (standard Apple numeric environment) and it 
 never bothered me to type all those characters. Even the name "real" 
 makes me cringe since I would expect "real" to be able to represent 
 irrational numbers like sqrt(2) - eg a real number. Maybe we can call it 
 "rat" for a "rational approximation to a real number". Then we'd have 
 "rat" "irat" and "crat". It would give new meaning to the phrase "what is 
 this crat?"


 I agree, I liked "extended".  I'd even go so far as to prefer 
 "extended_complex"; brevity should never be more important than clarity. I 
 objected to the change at the time.  But it's not like the current state 
 was an irrational move made out of ignorance.  Perhaps it would have been 
 better if it had been changed to something like "pont" or "curp"; no way 
 to confuse it with something else then.


I could picture either of
 float, double, real, ifloat, idouble, imaginary, cfloat, cdouble, complex
or
 float, double, extended, ifloat, idouble, iextended, cfloat, cdouble, 
cextended

The first is consistent with mathematical naming of "real", "imaginary" and 
"complex" while the second is consistent with prefixing the precision. Using 
the word "real", which is a matheamical word, to indicate precision doesn't 
seem like a workable solution. 


I strongly agree - there's been several people now who have suggested that
scientific computing types would dismiss D out of hand if things stay as-is (a
few actually used the term "laugh" independently of one another).

Another option:

float, double, intrinsic, ifloat, idouble, imaginary, cfloat, cdouble, complex

Intrinsic is perfect because it describes exactly what the type is, and on many
types of CPU, double and intrinsic will actually be the same. There may even be
some PDA's and such where intrinsic is smaller than a double. Likewise,
imaginary and complex are great because the lack of a prefix implies intrinsic.

- Dave
May 23 2005
prev sibling next sibling parent "Ben Hinkle" <ben.hinkle gmail.com> writes:
"Vegeta" <lord.vegeta ica.luz.ve> wrote in message 
news:d6qlno$2ct8$2 digitaldaemon.com...

 I'm new to the D language and I like what I've seen so far.
 But there is one thing that is wrong and it is the names of the types
 ireal  and creal.
 It looks like those names mean imaginary real and complex real.
 I suppose these types exist so that D is better suited to numerical
 programming. But anyone who knows a little mathematics will laugh at a
 language that has types with those absurd names.
 Having an int real makes much more sense.

 Those types should be called imaginary and complex.

 Probably this discussion has happened before, but just in case.


It has come up: http://www.digitalmars.com/d/archives/28044.html,
http://www.digitalmars.com/d/archives/9770.html
and probably more. Search around in the D archives linked off the main 
navigation bar.

I'm not aware of anyone who really likes the current names. Walter chose 
them because they are short, it seems. I haven't read the archives enough to 
see what happened to 'imaginary' and 'complex' since those look like the 
original names Walter chose.
May 22 2005
prev sibling parent "Lionello Lunesu" <lio lunesu.removethis.com> writes:
 Those types should be called imaginary and complex.


I agree.
The name "real" is indeed a little confusing.

I'm toying with my own type names lately, using just 'int' and 'float', and 
deriving all the others from these two names.

Most of the time, you don't care how many bits something has, and you'll 
just want the platform's standard size. These should be called "int" and 
"float".

If you do care about size, you should specify it, ie. when declaring structs 
meant for network/files: int16, uint32, int128,  float32, etc..

For floating point types there's the special case where you'd want the 
highest available precision. I have no idea what a good name for this type 
would be ("long float" comes to mind, since that's what "long" was meant to 
do in the first place).

The type names "short" and "long" are inherently confusing and should be 
deprecated, or aliased to int16, int32 respectively for portability reasons.

These are the guidelines I wish to follow for the rewrite of our company's 
game engine. Just some thoughts.

L.

PS. "char", "bit" and "byte" can stay, because of their special meanings 
(characters, boolean, unit)
May 23 2005