Create MOstrPower and start adding it into multiply

mapytex/calculus/core/compute/multiply.py

@@ -14,7 +14,7 @@ from multipledispatch import Dispatcher
 from ..tree import Tree
 from ..MO.mo import MO, MOnumber, MOstr
 from ..MO.fraction import MOFraction
-from ..MO.monomial import MOMonomial
+from ..MO.monomial import MOstrPower, MOMonomial
 from .exceptions import MultiplyError
 from .filters import special_case
 
@@ -175,18 +175,102 @@ def mostr_moscalar(left, right):
     """
     return MOMonomial(right, left)
 
+@multiply.register((MOnumber, MOFraction), MOstrPower)
+@special_case(multiply_filter)
+def moscalar_mostrpower(left, right):
+    """ Multiply a scalar with a MOstrPower
+
+    >>> a = MOnumber(4)
+    >>> x = MOstrPower('x', 4)
+    >>> print(multiply(a, x))
+    *
+     > 4
+     > ^
+     | > x
+     | > 4
+
+    """
+    return MOMonomial(left, right)
+
+@multiply.register(MOstrPower, (MOnumber, MOFraction))
+@special_case(multiply_filter)
+def mostrpower_moscalar(left, right):
+    """ Multiply a MOstrPower with a scalar
+
+    >>> a = MOnumber(4)
+    >>> x = MOstrPower('x', 4)
+    >>> print(multiply(x, a))
+    *
+     > 4
+     > ^
+     | > x
+     | > 4
+
+    """
+    return MOMonomial(right, left)
+
 @multiply.register((MOnumber, MOFraction), MOMonomial)
 @special_case(multiply_filter)
 def moscalar_monomonial(left, right):
     """ Multiply a scalar with a monomial
 
     >>> a = MOnumber(4)
-    >>> b = MOMonomial(5, 'x', 3)
+    >>> x = MOstrPower('x', 4)
+    >>> b = MOMonomial(5, x) 
+    >>> print(multiply(a, b))
+    *
+     > *
+     | > 4
+     | > 5
+     > ^
+     | > x
+     | > 4
 
-    # >>> print(multiply(a, b))
     """
-    coefficient = Tree('*', left, right._coefficient)
-    return Tree('*', coefficient, MOMonomial(1, right._variable, right._power))
+    coefficient = Tree('*', left, right.coefficient)
+    return Tree('*', coefficient, right.strpower)
+
+@multiply.register(MOMonomial, (MOnumber, MOFraction))
+@special_case(multiply_filter)
+def monomonial_moscalar(left, right):
+    """ Multiply a momonial with a scalar
+
+    >>> x = MOstrPower('x', 4)
+    >>> a = MOMonomial(5, x) 
+    >>> b = MOnumber(4)
+    >>> print(multiply(a, b))
+    *
+     > *
+     | > 4
+     | > 5
+     > ^
+     | > x
+     | > 4
+
+    """
+    coefficient = Tree('*', right, left.coefficient)
+    return Tree('*', coefficient, left.strpower)
+
+@multiply.register(MOstr, MOstrPower)
+@special_case(multiply_filter)
+def mostr_mostrpower(left, right):
+    """ Multiply a MOstr and a MOstrPower
+
+    >>> a = MOstr('x')
+    >>> b = MOstrPower('x', 4)
+    >>> multiply(a, b)
+    <MOstrPower x^5>
+    >>> a = MOstr('x')
+    >>> b = MOstrPower('y', 4)
+    >>> multiply(a, b)
+    Traceback (most recent call last):
+        ...
+    mapytex.calculus.core.compute.exceptions.MultiplyError: Can't multiply MOstr and MOstrPower if they don'thave same variable (got x and y)
+    """
+    if left.variable != right.variable:
+        raise MultiplyError("Can't multiply MOstr and MOstrPower if they don't"
+                f"have same variable (got {left.variable} and {right.variable})")
+    return MOstrPower(left.variable, right.power+1)
 
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