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#199 integrate(exp(-x^2)+exp(x)/x,x) ←	↑	→ #200 display of TwoDimensionalArray of type Union(...) is not properly formatted

#20 D(1, z) fails

Edit detail for #20 D(1, z) fails revision 2 of 3

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Editor: kratt6 Time: 2007/12/28 14:57:10 GMT-8
Note:

added:

From kratt6 Fri Dec 28 14:57:10 -0800 2007
From: kratt6
Date: Fri, 28 Dec 2007 14:57:10 -0800
Subject: 
Message-ID: <20071228145710-0800@axiom-wiki.newsynthesis.org>

Category: Axiom Mathematics => Axiom Interpreter

From: Vladimir Bondarenko Subject -- [Axiom-developer]? AXIOM BUG: D(1, z) Date -- Mon, 17 Jan 2005 07:35:49 +0200

Hi *,

A terrible bug in differentiation.

axiom
D(sin(z)^2+cos(z)^2, z)

(1)

Type: Expression Integer

axiom
D(simplify(sin(z)^2+cos(z)^2), z)

(2)

Type: Expression Integer

BUT

axiomD(1, z)
   There are 5 exposed and 0 unexposed library operations named D 
      having 2 argument(s) but none was determined to be applicable. 
      Use HyperDoc Browse, or issue
                                )display op D
      to learn more about the available operations. Perhaps 
      package-calling the operation or using coercions on the arguments
      will allow you to apply the operation.
   Cannot find a definition or applicable library operation named D 
      with argument type(s) 
                               PositiveInteger
                                 Variable z
      Perhaps you should use "@" to indicate the required return type, 
      or "$" to specify which version of the function you need.
D(cosh(z)^2-sinh(z)^2, z)

(3)

Type: Expression Integer

axiom
D(simplify(cosh(z)^2-sinh(z)^2), z)

(4)

Type: Expression Integer

wrong arument types: Mon, 17 Jan 2005 22:28:18 -0600 reply

D(1,z) is not a valid type signature. Try

axiom
D(1::Expression(Integer),z)

(5)

Type: Expression Integer

In Axiom it is important to know the type of the arguments to a function. In this case you gave the D function a PositveInteger? and is does not have a path to coerce PostiveInteger? -> Expression(Integer).

Whenever you see the message about exposed and unexposed library functions the meaning is that you didn't match the type of the arguments and the interpreter couldn't get there from here.

The coercion/conversion tower in the interpreter is not well defined and sometimes it needs help.