Fix: add special case to add typing

Sometimes, typing/add.py tried to build MOpolynomial with only one
coefficient.

mapytex/__init__.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 # encoding: utf-8
 
-from .calculus import Expression, Integer, Decimal, random_list
+from .calculus import Expression, Integer, Decimal, random_list, render, Polynomial, Fraction
 
 # Expression.set_render('tex')
 

mapytex/calculus/API/__init__.py

@@ -108,66 +108,35 @@ x^7
 (6 + 6) * x + 4x^2 + 9
 4x^2 + 12x + 9
 
->>> e = Expression.from_str("(2x+3)(-x+1)")
+>>> e = Expression.from_str("(2x-3)(-x+2)")
 >>> e_simplified = e.simplify()
 >>> e_simplified
-<Quadratic - 2x^2 - x + 3>
+<Quadratic - 2x^2 + 7x - 6>
 >>> for s in e_simplified.explain():
 ...    print(s)
-
+(2x - 3)(- x + 2)
+(2x - 3)(- x + 2)
+2x(- x) + 2x * 2 - 3(- x) - 3 * 2
+2(- 1) * x^(1 + 1) + 2 * 2 * x - 3(- 1) * x - 6
+4x + 3x - 2x^2 - 6
+(4 + 3) * x - 2x^2 - 6
+- 2x^2 + 7x - 6
 """
 
+from .renders import render
 from .expression import Expression
 from .tokens import Token
-from .tokens.number import Integer, Decimal
-
-
-def set_render(render):
-    """
-    :example:
-    >>> e = Expression.from_str("2+3*4")
-    >>> print(e)
-    2 + 3 * 4
-    >>> e = Expression.from_str("2+3/4")
-    >>> print(e)
-    2 + 3 / 4
-    >>> es = e.simplify()
-    >>> print(es)
-    11 / 4
-    >>> set_render('tex')
-    >>> Expression.RENDER
-    'tex'
-    >>> Token.RENDER
-    'tex'
-    >>> e = Expression.from_str("2+3*4")
-    >>> print(e)
-    2 + 3 \\times 4
-    >>> e = Expression.from_str("2+3/4")
-    >>> print(e)
-    2 + \\dfrac{3}{4}
-    >>> es = e.simplify()
-    >>> print(es)
-    \\dfrac{11}{4}
-    >>> set_render('txt')
-    """
-    Expression.set_render(render)
-    Token.set_render(render)
+from .tokens.polynomial import Polynomial
+from .tokens.number import Integer, Decimal, Fraction
 
 
 if __name__ == "__main__":
-    e = Expression.from_str("1+2/3/4/5")
-    et = e._typing()
-    print("typing")
-    print(e._tree)
-    e = et._order()
-    print("order")
-    print(e._tree)
-    e = e._optimize()
-    print("then optimize")
-    print(e._tree)
-    e = et._optimize()
-    print("optimize without order")
-    print(e._tree)
+    e = Expression.from_str("(2x-3)(-x+2)")
+    e_simplified = e.simplify()
+    e_simplified
+    for s in e_simplified.explain():
+        print(s._tree.map_on_leaf(lambda x: type(x)))
+        print(s)
 
 # -----------------------------
 # Reglages pour 'vim'

mapytex/calculus/API/expression.py

@@ -21,7 +21,7 @@ from ..core.random import (
 )
 from ..core.MO import moify
 from .tokens import factory
-from .renders import renders
+from .renders import render
 
 
 class Expression(object):
@@ -42,7 +42,6 @@ class Expression(object):
     14
     """
 
-    RENDER = "txt"
 
     def __init__(self, tree, ancestor=None):
         """
@@ -50,15 +49,6 @@ class Expression(object):
         self._tree = tree
         self._ancestor = ancestor
 
-    @classmethod
-    def set_render(cls, render):
-        """ Define default render function 
-
-        :param render: render name (txt or tex)
-
-        """
-        cls.RENDER = render
-
     @classmethod
     def from_str(cls, string, typing=True):
         """ Initiate the expression from a string
@@ -148,10 +138,10 @@ class Expression(object):
             return cls(t)
 
     def __str__(self):
-        return renders[self.RENDER](self._tree)
+        return render(self._tree)
 
     def __repr__(self):
-        return f"<Exp: {renders['txt'](self._tree)}>"
+        return f"<Exp: {render(self._tree, 'txt')}>"
 
     def _order(self, exclude_nodes=["*", "/", "**"]):
         """ Order the expression base on types
@@ -319,15 +309,15 @@ class Expression(object):
 
         comp_exp = opt_exp._compute()
 
-        if typed_exp == comp_exp:
-            typed_exp.set_ancestor(self._ancestor)
-            return typed_exp
-        else:
+        if typed_exp != comp_exp:
             comp_exp.set_ancestor(self)
             return comp_exp._simplify(optimize=optimize)
 
+        typed_exp.set_ancestor(self._ancestor)
+        return typed_exp
+
     def simplify(self, optimize=True):
-        """ Compute as much as possible the expression
+        """ Simplify the expression, keep the history and factory child
 
         :param optimize: bool to optimize tree when it's possible
         :return: an expression

mapytex/calculus/API/renders.py

@@ -12,34 +12,59 @@ Expression
 """
 from ..core import tree2txt, tree2tex
 
+class Render(object):
+    """ Object which render Expression or token """
 
-def _txt(mo_tree):
-    """ txt render for MOs or Trees"""
-    try:
-        return tree2txt(mo_tree)
-    except ValueError:
-        pass
+    def __init__(self, default="txt"):
+        self._default = default
+        self._render = default
+        self.renders = {}
 
-    try:
-        return mo_tree.__txt__
-    except AttributeError:
-        return str(mo_tree)
+    def register_render(self, name, func, attribute):
+        """ register a render """
+        try:
+            self.renders[name]
+        except KeyError:
+            self.renders[name] = {"name": name, "func": func, "attribute": attribute}
+        else:
+            raise ValueError("This render name already exists")
+
+    @property
+    def render_name(self):
+        return self._render
+
+    @property
+    def render(self):
+        return self.renders[self._render]
+
+    def __call__(self, mo_tree, tmp_render=''):
+        if tmp_render:
+            r = self.renders[tmp_render]
+        else:
+            r = self.render
+
+        try:
+            return r["func"](mo_tree)
+        except ValueError:
+            pass
+
+        try:
+            return getattr(mo_tree, r["attribute"])
+        except AttributeError:
+            return str(mo_tree)
+
+    def set_render(self, render):
+        """ Define the render """
+        if render in self.renders.keys():
+            self._render = render
+        else:
+            raise ValueError("This render does not exists")
 
 
-def _tex(mo_tree):
-    """ Tex render for MOs or Trees"""
-    try:
-        return tree2tex(mo_tree)
-    except ValueError:
-        pass
 
-    try:
-        return mo_tree.__tex__
-    except AttributeError:
-        return str(mo_tree)
-
-
-renders = {"txt": _txt, "tex": _tex}
+render = Render()
+render.register_render("txt", tree2txt, "__txt__")
+render.register_render("tex", tree2tex, "__tex__")
 
 # -----------------------------
 # Reglages pour 'vim'

mapytex/calculus/API/tokens/number.py

@@ -18,7 +18,7 @@ from ...core.MO import MO, MOnumber
 from ...core.MO.fraction import MOFraction
 from random import random
 
-__all__ = ["Integer", "Decimal"]
+__all__ = ["Integer", "Decimal", "Fraction"]
 
 
 class Integer(Token):
@@ -141,7 +141,7 @@ class Decimal(Token):
 
 class Fraction(Token):
 
-    """ Token representing a fraction
+    """ Token representing a fraction of numbers
 
     :example:
     >>> Fraction("3/4")
@@ -237,11 +237,25 @@ class Fraction(Token):
 
     @property
     def numerator(self):
-        return self._mo.numerator
+        """ Get numerator of the fraction
+
+        :example:
+        >>> a = Fraction("3/4")
+        >>> a.numerator
+        <Integer 3>
+        """
+        return Integer(self._mo.numerator)
 
     @property
     def denominator(self):
-        return self._mo.denominator
+        """ Get denominator of the fraction
+
+        :example:
+        >>> a = Fraction("3/4")
+        >>> a.denominator
+        <Integer 4>
+        """
+        return Integer(self._mo.denominator)
 
     @property
     def decimal(self):
@@ -255,7 +269,58 @@ class Fraction(Token):
         >>> f.decimal
         <Decimal 0.3333333333333333333333333333>
         """
-        return Decimal(_Decimal(self._mo.numerator._value) / _Decimal(self._mo.denominator._value))
+        return Decimal(self._mo._value)
+
+    @property
+    def simplified(self):
+        """ Get the irreductible version of self
+
+        :example:
+        >>> f = Fraction("3/4")
+        >>> f.simplified
+        <Fraction 3 / 4>
+        >>> f = Fraction("12/9")
+        >>> f.simplified
+        <Fraction 4 / 3>
+        >>> f = Fraction("12/4")
+        >>> f.simplified
+        <Integer 3>
+
+        """
+        simplified = self._mo.simplified()
+
+        if isinstance(simplified, MOnumber):
+            return Integer(simplified)
+
+        return Fraction(simplified)
+
+    def simplify(self):
+        """ Itself or its simplified version
+
+        :example:
+        >>> f = Fraction("12/8")
+        >>> fs = f.simplify()
+        >>> for i in fs.explain():
+        ...    print(i)
+        12 / 8
+        3 / 2
+        >>> f = Fraction("5/8")
+        >>> fs = f.simplify()
+        >>> for i in fs.explain():
+        ...    print(i)
+        5 / 8
+        """
+        simplified = self.simplified
+        try:
+            if self.numerator == simplified.numerator:
+                return self
+        except AttributeError:
+            pass
+
+        simplified._ancestor = self
+        return simplified
+
+
 
 
 # -----------------------------

mapytex/calculus/API/tokens/polynomial.py

@@ -15,6 +15,7 @@ from .token import Token
 from . import to_be_token
 from ...core.MO import MO
 from ...core.MO.atoms import moify
+from ...core.MO.polynomial import MOpolynomial
 
 __all__ = ["Polynomial", "Quadratic", "Linear"]
 
@@ -44,9 +45,21 @@ class Polynomial(Token):
         return cls(mo, name, ancestor)
 
     @classmethod
-    def from_coefficients(cls, coefficients):
-        """ Initiate polynomial from list of coefficients """
-        pass
+    def from_coefficients(cls, coefficients, variable_name="x", name=""):
+        """ Initiate polynomial from list of coefficients 
+
+        :examples:
+        >>> P = Polynomial.from_coefficients([1, 2, 3])
+        >>> P
+        <Polynomial 3x^2 + 2x + 1>
+        >>> P = Polynomial.from_coefficients([1, 2, -3])
+        >>> P
+        <Polynomial - 3x^2 + 2x + 1>
+        >>> P = Polynomial.from_coefficients([1, 2, 3], "y")
+        >>> P
+        <Polynomial 3y^2 + 2y + 1>
+        """
+        return cls(MOpolynomial(variable_name, coefficients), name)
 
     @classmethod
     def random(cls):
@@ -135,7 +148,11 @@ class Linear(Polynomial):
     >>> P.differentiate()
     <Integer 2>
     >>> P.roots
-    [<Fraction - 2 / 1>]
+    [<Integer - 2>]
+    >>> for i in P.roots[0].explain():
+    ...    print(i)
+    - 2 / 1
+    - 2
 
     """
 
@@ -177,9 +194,20 @@ class Linear(Polynomial):
         >>> from ...core.MO.polynomial import MOpolynomial, MOMonomial
         >>> P = Linear(MOpolynomial('x', [1, 2]))
         >>> P.roots
-        [<Fraction - 2 / 1>]
-        >>> #P = Linear(MOpolynomial('x', [1, -2]))
-        >>> #P.roots
+        [<Integer - 2>]
+        >>> P = Linear(MOpolynomial('x', [2, 1]))
+        >>> P.roots
+        [<Fraction - 1 / 2>]
+        >>> for i in P.roots[0].explain():
+        ...    print(i)
+        - 1 / 2
+        >>> P = Linear(MOpolynomial('x', [10, 6]))
+        >>> P.roots
+        [<Fraction - 3 / 5>]
+        >>> for i in P.roots[0].explain():
+        ...    print(i)
+        - 6 / 10
+        - 3 / 5
         """
 
         try:

mapytex/calculus/API/tokens/token.py

@@ -10,7 +10,7 @@
 Tokens: practical envelop of math object
 
 """
-from ..renders import renders
+from ..renders import render
 from ...core.MO.atoms import moify
 
 
@@ -18,8 +18,6 @@ class Token(object):
 
     """ Token: practical envelop of an math object """
 
-    RENDER = "txt"
-
     def __init__(self, mo, name="", ancestor=None):
         self._mo = mo
         self.name = name
@@ -34,14 +32,6 @@ class Token(object):
     ):
         raise NotImplemented
 
-    @classmethod
-    def set_render(cls, render):
-        """ Define default render function
-
-        :param render: render name (txt or tex)
-        """
-        cls.RENDER = render
-
     def explain(self):
         """ Yield every calculus step which have lead to self
 
@@ -64,10 +54,16 @@ class Token(object):
             yield self
 
     def __repr__(self):
-        return f"<{self.__class__.__name__} {renders['txt'](self._mo)}>"
+        try:
+            return f"<{self.__class__.__name__} {render(self._mo._tree, 'txt')}>"
+        except AttributeError:
+            return f"<{self.__class__.__name__} {render(self._mo, 'txt')}>"
 
     def __str__(self):
-        return renders[self.RENDER](self._mo)
+        try:
+            return render(self._mo._tree)
+        except AttributeError:
+            return render(self._mo)
 
     @property
     def raw(self):

mapytex/calculus/__init__.py

@@ -13,7 +13,7 @@ Make calculus as a student
 Expression is the classe wich handle all calculus. It can randomly generate or import calculus, simplify them and explain them as a student would do.
 
 >>> from mapytex.calculus import Expression
->>> Expression.set_render("txt")
+>>> render.set_render("txt")
 >>> e = Expression.from_str("2x + 6 - 3x")
 >>> print(e)
 2x + 6 - 3x
@@ -30,7 +30,7 @@ Expression is the classe wich handle all calculus. It can randomly generate or i
 
 """
 
-from .API import Expression, Integer, Decimal
+from .API import Expression, Integer, Decimal, render, Polynomial, Fraction
 from .core import random_list
 from decimal import getcontext
 #getcontext().prec = 2

mapytex/calculus/core/MO/fraction.py

@@ -9,6 +9,8 @@
 from mapytex.calculus.core.tree import Tree
 from .mo import Molecule, MO
 from .atoms import MOnumber
+from decimal import Decimal
+from ..arithmetic import gcd
 
 __all__ = ["MOFraction"]
 
@@ -70,6 +72,10 @@ class MOFraction(Molecule):
     def denominator(self):
         return self._denominator
 
+    @property
+    def _value(self):
+        return Decimal(self._numerator._value) / Decimal(self._denominator._value)
+
     def inverse(self):
         """ return the inverse fraction """
         return MOFraction(self._denominator, self._numerator, self.negative)
@@ -90,6 +96,37 @@ class MOFraction(Molecule):
         else:
             raise NotImplementedError
 
+    def simplified(self):
+        """ Simplified version of self 
+
+        :examplex
+        >>> f = MOFraction(2, 3)
+        >>> f
+        <MOFraction 2 / 3>
+        >>> f.simplified()
+        <MOFraction 2 / 3>
+        >>> f = MOFraction(2, 6)
+        >>> f
+        <MOFraction 2 / 6>
+        >>> f.simplified()
+        <MOFraction 1 / 3>
+        >>> f = MOFraction(32, 24)
+        >>> f.simplified()
+        <MOFraction 4 / 3>
+        >>> f = MOFraction(32, 8)
+        >>> f.simplified()
+        <MOnumber 4>
+        """
+        frac_gcd = gcd(self.numerator._value, self.denominator._value) 
+        new_num = self.numerator._value / frac_gcd
+        new_denom = self.denominator._value / frac_gcd
+
+        if new_denom == 1:
+            return MOnumber(new_num)
+
+        return MOFraction(new_num, new_denom)
+
+
 
 # -----------------------------
 # Reglages pour 'vim'

mapytex/calculus/core/MO/monomial.py

@@ -132,7 +132,7 @@ class MOstrPower(Molecule):
 
 class MOMonomial(Molecule):
 
-    """ Monomial math object"""
+    """ Monomial math object : ax^n"""
 
     MAINOP = "*"
 

mapytex/calculus/core/MO/polynomial.py

@@ -18,7 +18,7 @@ __all__ = ["MOpolynomial"]
 
 class MOpolynomial(Molecule):
 
-    """ MO polynomial"""
+    """ MO polynomial: ax^n + ... + z (can't be a monomial)"""
 
     MAINOP = "+"
 
@@ -39,6 +39,14 @@ class MOpolynomial(Molecule):
         <MOpolynomial 4x^3 + 1>
         >>> MOpolynomial('x', {0: 1, 3: 1})
         <MOpolynomial x^3 + 1>
+        >>> MOpolynomial('x', [0, 0, 3])
+        Traceback (most recent call last):
+        ...
+        TypeError: A MOpolynomial can't be monomial it has to have more than one coefficient.
+        >>> MOpolynomial('x', {3: 1})
+        Traceback (most recent call last):
+        ...
+        TypeError: A MOpolynomial can't be monomial it has to have more than one coefficient.
 
         """
         _variable = MO.factory(variable)
@@ -58,6 +66,9 @@ class MOpolynomial(Molecule):
             raise TypeError("Coefs needs to be a dictionnary or a list")
         self._coefs = _coefs
 
+        if len(self._coefs) == 1:
+            raise TypeError("A MOpolynomial can't be monomial it has to have more than one coefficient.")
+
         monomials = OrderedDict()
         for deg in sorted(self._coefs.keys()):
             coef = self._coefs[deg]

mapytex/calculus/core/renders/tree2tex.py

@@ -91,9 +91,11 @@ def mul2tex(left, right):
     '- 3x'
     >>> mul2tex(a, a)
     'x \\times x'
+    >>> mul2tex(a, MO.factory(-3))
+    'x(- 3)'
     """
     left_ = render_with_parenthesis(left, "*")
-    right_ = render_with_parenthesis(right, "*")
+    right_ = render_with_parenthesis(right, "*", is_at_right=True)
 
     display_time = True
     # if (right_[0].isalpha() and (left_.isnumeric() or left_.isdecimal())) or right_[
@@ -183,23 +185,17 @@ def pow2tex(left, right):
     return f"{left_}^{{{right_}}}"
 
 
-def render_with_parenthesis(subtree, operator):
+def render_with_parenthesis(subtree, operator, is_at_right=False):
     subtree_need_parenthesis = False
     try:
         subtree.node
     except AttributeError:
-        try:
-            if (
-                OPERATORS[subtree.MAINOP]["precedence"]
-                < OPERATORS[operator]["precedence"]
-            ):
-                subtree_need_parenthesis = True
-        except (AttributeError, KeyError):
-            pass
         try:
             subtree_ = subtree.__tex__
         except AttributeError:
             subtree_ = str(subtree)
+        if subtree_.startswith("-") and OPERATORS["-"]["precedence"] < OPERATORS[operator]["precedence"] and is_at_right:
+            subtree_need_parenthesis = True
     else:
         if OPERATORS[subtree.node]["precedence"] < OPERATORS[operator]["precedence"]:
             subtree_need_parenthesis = True

mapytex/calculus/core/renders/tree2txt.py

@@ -91,11 +91,13 @@ def mul2txt(left, right):
     '- 3x'
     >>> mul2txt(a, a)
     'x * x'
+    >>> mul2txt(a, MO.factory(-3))
+    'x(- 3)'
     """
     display_time = True
 
     left_ = render_with_parenthesis(left, "*")
-    right_ = render_with_parenthesis(right, "*")
+    right_ = render_with_parenthesis(right, "*", is_at_right=True)
 
     if right_[0].isalpha():
         # TODO: C'est bien beurk en dessous... |ven. déc. 21 12:03:07 CET 2018
@@ -187,23 +189,22 @@ def pow2txt(left, right):
     return f"{left_}^{right_}"
 
 
-def render_with_parenthesis(subtree, operator):
+def tree_with_parenthesis(subtree, operator):
+    """ Assuming the subtree is a tree, then have .node """
+    pass
+
+
+def render_with_parenthesis(subtree, operator, is_at_right=False):
     subtree_need_parenthesis = False
     try:
         subtree.node
     except AttributeError:
-        try:
-            if (
-                OPERATORS[subtree.MAINOP]["precedence"]
-                < OPERATORS[operator]["precedence"]
-            ):
-                subtree_need_parenthesis = True
-        except (AttributeError, KeyError):
-            pass
         try:
             subtree_ = subtree.__txt__
         except AttributeError:
             subtree_ = str(subtree)
+        if subtree_.startswith("-") and OPERATORS["-"]["precedence"] < OPERATORS[operator]["precedence"] and is_at_right:
+            subtree_need_parenthesis = True
     else:
         if OPERATORS[subtree.node]["precedence"] < OPERATORS[operator]["precedence"]:
             subtree_need_parenthesis = True

mapytex/calculus/core/typing/add.py

@@ -11,11 +11,11 @@ Add MO with typing
 """
 
 from multipledispatch import Dispatcher
-from ..tree import Tree
-from ..MO import MO, MOnumber, MOstr
+from ..MO import MOnumber, MOstr
 from ..MO.monomial import MOstrPower, MOMonomial
 from ..MO.polynomial import MOpolynomial
 from ..MO.fraction import MOFraction
+from ..compute.filters import special_case
 
 add_doc = """ Add MOs
 
@@ -27,8 +27,26 @@ add_doc = """ Add MOs
 
 add = Dispatcher("add", doc=add_doc)
 
+def add_filter(left, right):
+    """ Special cases for add MO (adding 0) 
+
+    :param left: MO
+    :param right: MO
+    :returns: MO if it is a special case, nothing other wise
+    """
+    try:
+        if left == 0:
+            return right
+    except TypeError:
+        pass
+    try:
+        if right == 0:
+            return left
+    except TypeError:
+        pass
 
 @add.register((MOnumber, MOFraction), MOstr)
+@special_case(add_filter)
 def moscalar_mostr(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -39,11 +57,15 @@ def moscalar_mostr(left, right):
     >>> a = MOFraction(1, 5)
     >>> add(a, b)
     <MOpolynomial x + 1 / 5>
+    >>> a = MOnumber(0)
+    >>> add(a, b)
+    <MOstr x>
     """
     return MOpolynomial(right, [left, 1])
 
 
 @add.register(MOstr, (MOnumber, MOFraction))
+@special_case(add_filter)
 def mostr_moscalar(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -54,11 +76,15 @@ def mostr_moscalar(left, right):
     >>> b = MOFraction(1, 5)
     >>> add(a, b)
     <MOpolynomial x + 1 / 5>
+    >>> b = MOnumber(0)
+    >>> add(a, b)
+    <MOstr x>
     """
     return MOpolynomial(left, [right, 1])
 
 
 @add.register((MOnumber, MOFraction), MOstrPower)
+@special_case(add_filter)
 def moscalar_mostrpower(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -74,6 +100,7 @@ def moscalar_mostrpower(left, right):
 
 
 @add.register(MOstrPower, (MOnumber, MOFraction))
+@special_case(add_filter)
 def mostrpower_moscalar(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -89,6 +116,7 @@ def mostrpower_moscalar(left, right):
 
 
 @add.register((MOnumber, MOFraction), MOMonomial)
+@special_case(add_filter)
 def moscalar_momonomial(left, right):
     """ add a scalar with a MOMonomial to create a MOpolynomial
 
@@ -99,11 +127,17 @@ def moscalar_momonomial(left, right):
     >>> a = MOFraction(1, 5)
     >>> add(a, b)
     <MOpolynomial 3x^4 + 1 / 5>
+
+    >>> a = MOnumber(0)
+    >>> b = MOMonomial(2, 'x', 4)
+    >>> add(a, b)
+    <MOMonomial 2x^4>
     """
     return MOpolynomial(right.variable, {right.power: right.coefficient, 0: left})
 
 
 @add.register(MOMonomial, (MOnumber, MOFraction))
+@special_case(add_filter)
 def momonial_moscalar(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -115,11 +149,17 @@ def momonial_moscalar(left, right):
     >>> add(a, b)
     <MOpolynomial 3x^4 + 1 / 5>
 
+    >>> a = MOMonomial(2, 'x', 4)
+    >>> b = MOnumber(0)
+    >>> add(a, b)
+    <MOMonomial 2x^4>
+
     """
     return MOpolynomial(left.variable, {0: right, left.power: left.coefficient})
 
 
 @add.register((MOnumber, MOFraction), MOpolynomial)
+@special_case(add_filter)
 def moscalar_mopolynomial(left, right):
     """ add a scalar with a MOpolynomial to create a MOpolynomial
 
@@ -143,6 +183,7 @@ def moscalar_mopolynomial(left, right):
 
 
 @add.register(MOpolynomial, (MOnumber, MOFraction))
+@special_case(add_filter)
 def mopolynomial_moscalar(left, right):
     """ add a scalar with a MOpolynomial to create a MOpolynomial
 
@@ -164,6 +205,7 @@ def mopolynomial_moscalar(left, right):
 
 
 @add.register(MOstr, MOstr)
+@special_case(add_filter)
 def mostr_mostr(left, right):
     """ add 2 mostr
 
@@ -178,6 +220,7 @@ def mostr_mostr(left, right):
 
 
 @add.register(MOstr, MOstrPower)
+@special_case(add_filter)
 def mostr_mostrpower(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -195,6 +238,7 @@ def mostr_mostrpower(left, right):
 
 
 @add.register(MOstrPower, MOstr)
+@special_case(add_filter)
 def mostrpower_mostr(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -212,6 +256,7 @@ def mostrpower_mostr(left, right):
 
 
 @add.register(MOstrPower, MOstrPower)
+@special_case(add_filter)
 def mostrpower_mostrpower(left, right):
     """ add 2 mostrpower
 
@@ -231,6 +276,7 @@ def mostrpower_mostrpower(left, right):
 
 
 @add.register(MOstr, MOpolynomial)
+@special_case(add_filter)
 def mostr_mopolynomial(left, right):
     """ add a str with a MOpolynomial to create a MOpolynomial
 
@@ -249,6 +295,7 @@ def mostr_mopolynomial(left, right):
 
 
 @add.register(MOpolynomial, MOstr)
+@special_case(add_filter)
 def mopolynomial_mostr(left, right):
     """ add a str with a MOpolynomial to create a MOpolynomial
 
@@ -266,6 +313,7 @@ def mopolynomial_mostr(left, right):
 
 
 @add.register(MOstrPower, MOpolynomial)
+@special_case(add_filter)
 def mostrpower_mopolynomial(left, right):
     """ add a strPower with a MOpolynomial to create a MOpolynomial
 
@@ -284,6 +332,7 @@ def mostrpower_mopolynomial(left, right):
 
 
 @add.register(MOpolynomial, MOstrPower)
+@special_case(add_filter)
 def mopolynomial_mostrpower(left, right):
     """ add a strPower with a MOpolynomial to create a MOpolynomial
 
@@ -301,6 +350,7 @@ def mopolynomial_mostrpower(left, right):
 
 
 @add.register(MOMonomial, MOpolynomial)
+@special_case(add_filter)
 def momonomial_mopolynomial(left, right):
     """ add a Monomial with a MOpolynomial to create a MOpolynomial
 
@@ -319,6 +369,7 @@ def momonomial_mopolynomial(left, right):
 
 
 @add.register(MOpolynomial, MOMonomial)
+@special_case(add_filter)
 def mopolynomial_momonomial(left, right):
     """ add a Monomial with a MOpolynomial to create a MOpolynomial
 
@@ -336,6 +387,7 @@ def mopolynomial_momonomial(left, right):
 
 
 @add.register(MOpolynomial, MOpolynomial)
+@special_case(add_filter)
 def mopolynomial_mopolynomial(left, right):
     """ add a polynomial with a MOpolynomial to create a MOpolynomial
 
@@ -355,6 +407,7 @@ def mopolynomial_mopolynomial(left, right):
 
 
 @add.register(MOstr, MOMonomial)
+@special_case(add_filter)
 def mostr_monomial(left, right):
     """ add a mostr with a MOMonomial to create a MOpolynomial
 
@@ -370,6 +423,7 @@ def mostr_monomial(left, right):
 
 
 @add.register(MOMonomial, MOstr)
+@special_case(add_filter)
 def monomial_mostr(left, right):
     """ add a mostr with a MOMonomial to create a MOpolynomial
 
@@ -385,6 +439,7 @@ def monomial_mostr(left, right):
 
 
 @add.register(MOstrPower, MOMonomial)
+@special_case(add_filter)
 def mostrpower_monomial(left, right):
     """ add a mostrPower with a MOMonomial to create a MOpolynomial
 
@@ -402,6 +457,7 @@ def mostrpower_monomial(left, right):
 
 
 @add.register(MOMonomial, MOstrPower)
+@special_case(add_filter)
 def monomial_mostrpower(left, right):
     """ add a mostrPower with a MOMonomial to create a MOpolynomial
 
@@ -419,6 +475,7 @@ def monomial_mostrpower(left, right):
 
 
 @add.register(MOMonomial, MOMonomial)
+@special_case(add_filter)
 def monomial_momonomial(left, right):
     """ add a moMonomial with a MOMonomial to create a MOpolynomial
 

test/calculus/core/test_render.py

@@ -0,0 +1,31 @@
+import mapytex
+
+def test_default_render():
+    assert mapytex.render.render_name == "txt"
+
+def test_default_rending():
+    e = mapytex.Expression("2*3")
+    assert str(e) == "2*3"
+
+def test_changing_render():
+    assert mapytex.render.render_name == "txt"
+    mapytex.render.set_render("tex")
+    assert mapytex.render.render_name == "tex"
+    mapytex.render.set_render("txt")
+    assert mapytex.render.render_name == "txt"
+
+
+def test_changing_rending():
+    e = mapytex.Expression.from_str("2*3")
+    f = mapytex.Fraction("2/3")
+    assert str(e) == "2 * 3"
+    assert str(f) == "2 / 3"
+    mapytex.render.set_render("tex")
+    assert str(e) == "2 \\times 3"
+    assert str(f) == "\\dfrac{2}{3}"
+    mapytex.render.set_render("txt")
+    assert str(e) == "2 * 3"
+    assert str(f) == "2 / 3"
+
+
+