Re: [fricas-devel] Hypercomplex numbers

2010-03-19 Thread Bill Page
Rather than "lying" or expecting the system prove that "x^2+1 is irreducible in R" I think the usual approach in Axiom would be to introduce a declaration in the algebra library to this effect, i.e. introduce a new category such as "Irreducible(x^2+1,R)". On Fri, Mar 19, 2010 at 3:31 AM, Ralf He

Re: [fricas-devel] Hypercomplex numbers

2010-03-19 Thread Ralf Hemmecke
c(a + %i b) + d(a + %i b)%j but if we try to multiply these out ca + c %i b + da%j + d %i b%j which implies a new algebra which is not completely defined, for instance, we have some freedom to choose the properties of %i%j without violating the correctness of both inner and outer complex nu

Re: [fricas-devel] Hypercomplex numbers

2010-03-19 Thread Martin Baker
On Friday 19 Mar 2010 00:40:20 Bill Page wrote: > On Thu, Mar 18, 2010 at 8:27 PM, Waldek Hebisch wrote: > I think that to understand Waldek's point it is import to look at > ComplexCategory. > > http://axiom-wiki.newsynthesis.org/Complex > > E.g. > > if R has IntegralDomain then >I

Re: [fricas-devel] Hypercomplex numbers

2010-03-19 Thread Ralf Hemmecke
I think that to understand Waldek's point it is import to look at ComplexCategory. if R has Field then-- this is a lie; we must know that Field-- x^2+1 is irreducible in R Exactly. If we want to do mathematics, why do you distribute lies? Unfortunate

Re: [fricas-devel] Hypercomplex numbers

2010-03-18 Thread Bill Page
On Thu, Mar 18, 2010 at 8:27 PM, Waldek Hebisch wrote: > Ralf Hemmecke wrote: >> On 03/18/2010 11:17 PM, Waldek Hebisch wrote: >> > >> > It is a math problem: if base R is a field that does not contain >> > square root of -1, then Complex(R) is again a field.  But we have >> > no way to check this

Re: [fricas-devel] Hypercomplex numbers

2010-03-18 Thread Waldek Hebisch
Ralf Hemmecke wrote: > On 03/18/2010 11:17 PM, Waldek Hebisch wrote: > > > > It is a math problem: if base R is a field that does not contain > > square root of -1, then Complex(R) is again a field. But we have > > no way to check this condition, so need hardcode the choice. To > > allow building

Re: [fricas-devel] Hypercomplex numbers

2010-03-18 Thread Ralf Hemmecke
On 03/18/2010 11:17 PM, Waldek Hebisch wrote: Bill Page wrote: On Thu, Mar 18, 2010 at 1:53 PM, Martin Baker wrote: ... The problem is that complex numbers are defined over CommutativeRing and even types like this are not valid. (1) -> myType:Complex Complex Integer ? Complex(Complex(Integer)

Re: [fricas-devel] Hypercomplex numbers

2010-03-18 Thread Waldek Hebisch
Bill Page wrote: > On Thu, Mar 18, 2010 at 1:53 PM, Martin Baker wrote: > > ... > > The problem is that complex numbers are defined over CommutativeRing > > and even types like this are not valid. > > (1) -> myType:Complex Complex Integer > > > > ? Complex(Complex(Integer)) is not a valid type. > >

Re: [fricas-devel] Hypercomplex numbers

2010-03-18 Thread Waldek Hebisch
Martin Baker wrote: > How would one go about building a set of domains to represent > hypercomplex numbers without defining each one individually as a > separate domain? For example: complex numbers, double numbers, dual > numbers, dual complex, dual quaternion, dual vectors, split complex, > split

Re: [fricas-devel] Hypercomplex numbers

2010-03-18 Thread Bill Page
On Thu, Mar 18, 2010 at 1:53 PM, Martin Baker wrote: > ... > The problem is that complex numbers are defined over CommutativeRing > and even types like this are not valid. > (1) -> myType:Complex Complex Integer > >   Complex(Complex(Integer)) is not a valid type. > (1) -> > > Even if this was acce

[fricas-devel] Hypercomplex numbers

2010-03-18 Thread Martin Baker
How would one go about building a set of domains to represent hypercomplex numbers without defining each one individually as a separate domain? For example: complex numbers, double numbers, dual numbers, dual complex, dual quaternion, dual vectors, split complex, split quaternion and so on. What I