def apply(self, f, i, evaluation):
'Root[f_, i_]'
try:
if not f.has_form('Function', 1):
raise sympy.PolynomialError
body = f.leaves[0]
poly = body.replace_slots([f, Symbol('_1')], evaluation)
idx = i.to_sympy() - 1
# Check for negative indeces (they are not allowed in Mathematica)
if idx < 0:
evaluation.message('Root', 'iidx', i)
return
r = sympy.CRootOf(poly.to_sympy(), idx)
except sympy.PolynomialError:
evaluation.message('Root', 'nuni', f)
return
except TypeError:
evaluation.message('Root', 'nint', i)
return
except IndexError:
evaluation.message('Root', 'iidx', i)
return
return from_sympy(r)
def apply(self, f, x, x0, evaluation, options):
"FindRoot[f_, {x_, x0_}, OptionsPattern[]]"
# First, determine x0 and x
x0 = apply_N(x0, evaluation)
if not isinstance(x0, Number):
evaluation.message("FindRoot", "snum", x0)
return
x_name = x.get_name()
if not x_name:
evaluation.message("FindRoot", "sym", x, 2)
return
# Now, get the explicit form of f, depending of x
# keeping x without evaluation (Like inside a "Block[{x},f])
f = dynamic_scoping(lambda ev: f.evaluate(ev), {x_name: None},
evaluation)
# If after evaluation, we get an "Equal" expression,
# convert it in a function by substracting both
# members. Again, ensure the scope in the evaluation
if f.get_head_name() == "System`Equal":
f = Expression("Plus", f.leaves[0],
Expression("Times", Integer(-1), f.leaves[1]))
f = dynamic_scoping(lambda ev: f.evaluate(ev), {x_name: None},
evaluation)
# Determine the method
method = options["System`Method"]
if isinstance(method, Symbol):
method = method.get_name().split("`")[-1]
if method == "Automatic":
method = "Newton"
elif not isinstance(method, String):
method = None
evaluation.message("FindRoot", "bdmthd", method,
[String(m) for m in self.methods.keys()])
return
else:
method = method.value
# Determine the "jacobian"
if method in ("Newton", ) and options["System`Jacobian"].sameQ(
Symbol("Automatic")):
def diff(evaluation):
return Expression("D", f, x).evaluate(evaluation)
d = dynamic_scoping(diff, {x_name: None}, evaluation)
options["System`Jacobian"] = d
method = self.methods.get(method, None)
if method is None:
evaluation.message("FindRoot", "bdmthd", method,
[String(m) for m in self.methods.keys()])
return
x0, success = method(f, x0, x, options, evaluation)
if not success:
return
return Expression(SymbolList, Expression(SymbolRule, x, x0))
def to_sympy(self, expr, **kwargs):
try:
if not expr.has_form('Root', 2):
return None
f = expr.leaves[0]
if not f.has_form('Function', 1):
return None
body = f.leaves[0].replace_slots([f, Symbol('_1')], None)
poly = body.to_sympy(**kwargs)
i = expr.leaves[1].get_int_value(**kwargs)
if i is None:
return None
return sympy.CRootOf(poly, i)
except:
return None
def find_root_newton(f, x0, x, opts, evaluation) -> (Number, bool):
df = opts["System`Jacobian"]
maxit = opts["System`MaxIterations"]
x_name = x.get_name()
if maxit.sameQ(Symbol("Automatic")):
maxit = 100
else:
maxit = maxit.evaluate(evaluation).get_int_value()
def sub(evaluation):
d_value = df.evaluate(evaluation)
if d_value == Integer(0):
return None
return Expression(
"Times", f, Expression("Power", d_value, Integer(-1))
).evaluate(evaluation)
count = 0
while count < maxit:
minus = dynamic_scoping(sub, {x_name: x0}, evaluation)
if minus is None:
evaluation.message("FindRoot", "dsing", x, x0)
return x0, False
x1 = Expression("Plus", x0, Expression("Times", Integer(-1), minus)).evaluate(
evaluation
)
if not isinstance(x1, Number):
evaluation.message("FindRoot", "nnum", x, x0)
return x0, False
# TODO: use Precision goal...
if x1 == x0:
break
x0 = Expression(SymbolN, x1).evaluate(
evaluation
) # N required due to bug in sympy arithmetic
count += 1
else:
evaluation.message("FindRoot", "maxiter")
return x0, True
def find_root_secant(f, x0, x, opts, evaluation) -> (Number, bool):
region = opts.get("$$Region", None)
if not type(region) is list:
if x0.is_zero:
region = (Real(-1), Real(1))
else:
xmax = 2 * x0.to_python()
xmin = -2 * x0.to_python()
if xmin > xmax:
region = (Real(xmax), Real(xmin))
else:
region = (Real(xmin), Real(xmax))
maxit = opts["System`MaxIterations"]
x_name = x.get_name()
if maxit.sameQ(Symbol("Automatic")):
maxit = 100
else:
maxit = maxit.evaluate(evaluation).get_int_value()
x0 = from_python(region[0])
x1 = from_python(region[1])
f0 = dynamic_scoping(lambda ev: f.evaluate(evaluation), {x_name: x0},
evaluation)
f1 = dynamic_scoping(lambda ev: f.evaluate(evaluation), {x_name: x1},
evaluation)
if not isinstance(f0, Number):
return x0, False
if not isinstance(f1, Number):
return x0, False
f0 = f0.to_python(n_evaluation=True)
f1 = f1.to_python(n_evaluation=True)
count = 0
while count < maxit:
if f0 == f1:
x1 = Expression(
"Plus",
x0,
Expression(
"Times",
Real(0.75),
Expression("Plus", x1, Expression("Times", Integer(-1),
x0)),
),
)
x1 = x1.evaluate(evaluation)
f1 = dynamic_scoping(lambda ev: f.evaluate(evaluation),
{x_name: x1}, evaluation)
if not isinstance(f1, Number):
return x0, False
f1 = f1.to_python(n_evaluation=True)
continue
inv_deltaf = from_python(1.0 / (f1 - f0))
num = Expression(
"Plus",
Expression("Times", x0, f1),
Expression("Times", x1, f0, Integer(-1)),
)
x2 = Expression("Times", num, inv_deltaf)
x2 = x2.evaluate(evaluation)
f2 = dynamic_scoping(lambda ev: f.evaluate(evaluation), {x_name: x2},
evaluation)
if not isinstance(f2, Number):
return x0, False
f2 = f2.to_python(n_evaluation=True)
f1, f0 = f2, f1
x1, x0 = x2, x1
if x1 == x0 or abs(f2) == 0:
break
count = count + 1
else:
evaluation.message("FindRoot", "maxiter")
return x0, False
return x0, True
SymbolFalse,
SymbolList,
SymbolRule,
SymbolUndefined,
from_python,
)
from mathics.core.convert import sympy_symbol_prefix, SympyExpression, from_sympy
from mathics.core.rules import Pattern
from mathics.core.numbers import dps
from mathics.builtin.scoping import dynamic_scoping
from mathics.builtin.numeric import apply_N
from mathics import Symbol
import sympy
SymbolPlus = Symbol("Plus")
SymbolTimes = Symbol("Times")
SymbolPower = Symbol("Power")
IntegerZero = Integer(0)
IntegerMinusOne = Integer(-1)
class D(SympyFunction):
"""
<dl>
<dt>'D[$f$, $x$]'
<dd>gives the partial derivative of $f$ with respect to $x$.
<dt>'D[$f$, $x$, $y$, ...]'
<dd>differentiates successively with respect to $x$, $y$, etc.
<dt>'D[$f$, {$x$, $n$}]'
<dd>gives the multiple derivative of order $n$.
