Speed up sol[UnaryExpr] via C-level math and refactor UnaryExpr

CHANGELOG.md

@@ -9,6 +9,7 @@
 ### Changed
 - Move magic methods (`__radd__`, `__sub__`, `__rsub__`, `__rmul__`, `__richcmp__`, `__neg__`, and `__rtruediv__`) to `ExprLike` base class (#1204)
 - Speed up `Expr.__add__` and `Expr.__iadd__` via the C-level API
+- Replace Python math with C-level math functions and refactor unary expressions.
 ### Removed
 
 ## 6.2.1 - 2026.05.16

src/pyscipopt/expr.pxi

@@ -42,7 +42,6 @@
 # which should, in princple, modify the expr. However, since we do not implement __isub__, __sub__
 # gets called (I guess) and so a copy is returned.
 # Modifying the expression directly would be a bug, given that the expression might be re-used by the user. </pre>
-import math
 from typing import TYPE_CHECKING, Literal, Union
 
 import numpy as np
@@ -54,6 +53,12 @@ from cpython.number cimport PyNumber_Check
 from cpython.object cimport Py_LE, Py_EQ, Py_GE, Py_TYPE
 from cpython.ref cimport PyObject
 from cpython.tuple cimport PyTuple_GET_ITEM
+from libc.math cimport cos as c_cos
+from libc.math cimport exp as c_exp
+from libc.math cimport fabs as c_fabs
+from libc.math cimport log as c_log
+from libc.math cimport sqrt as c_sqrt
+from libc.math cimport sin as c_sin
 
 cimport numpy as cnp
 from pyscipopt.scip cimport Variable, Solution
@@ -281,23 +286,28 @@ cdef class ExprLike:
     def __pos__(self, /) -> Union[Expr, GenExpr]:
         return self.copy()
 
-    def __abs__(self) -> GenExpr:
-        return UnaryExpr(Operator.fabs, buildGenExprObj(self))
+    def __abs__(self, /) -> AbsExpr:
+        return AbsExpr(Operator.fabs, buildGenExprObj(self))
 
-    def exp(self) -> GenExpr:
-        return UnaryExpr(Operator.exp, buildGenExprObj(self))
+    def exp(self, /) -> ExpExpr:
+        return ExpExpr(Operator.exp, buildGenExprObj(self))
 
-    def log(self) -> GenExpr:
-        return UnaryExpr(Operator.log, buildGenExprObj(self))
+    def log(self, /) -> LogExpr:
+        return LogExpr(Operator.log, buildGenExprObj(self))
 
-    def sqrt(self) -> GenExpr:
-        return UnaryExpr(Operator.sqrt, buildGenExprObj(self))
+    def sqrt(self, /) -> SqrtExpr:
+        return SqrtExpr(Operator.sqrt, buildGenExprObj(self))
 
-    def sin(self) -> GenExpr:
-        return UnaryExpr(Operator.sin, buildGenExprObj(self))
+    def sin(self, /) -> SinExpr:
+        return SinExpr(Operator.sin, buildGenExprObj(self))
 
-    def cos(self) -> GenExpr:
-        return UnaryExpr(Operator.cos, buildGenExprObj(self))
+    def cos(self, /) -> CosExpr:
+        return CosExpr(Operator.cos, buildGenExprObj(self))
+
+    cpdef double _evaluate(self, Solution sol) except *:
+        raise NotImplementedError(
+            f"{self.__class__.__name__!s} need to implement _evaluate() method"
+        )
 
     cdef ExprLike copy(self, bint copy=True):
         raise NotImplementedError(
@@ -828,24 +838,54 @@ cdef class PowExpr(GenExpr):
         return res
 
 
-# Exp, Log, Sqrt, Sin, Cos Expressions
 cdef class UnaryExpr(GenExpr):
+
     def __init__(self, op, expr):
         self.children = []
         self.children.append(expr)
         self._op = op
 
-    def __abs__(self) -> UnaryExpr:
-        if self._op == "abs":
-            return <UnaryExpr>self.copy()
-        return UnaryExpr(Operator.fabs, self)
-
-    def __repr__(self):
+    def __repr__(self) -> str:
         return self._op + "(" + self.children[0].__repr__() + ")"
 
+
+cdef class AbsExpr(UnaryExpr):
+
+    def __abs__(self) -> AbsExpr:
+        return <AbsExpr>self.copy()
+
+    cpdef double _evaluate(self, Solution sol) except *:
+        return c_fabs((<GenExpr>self.children[0])._evaluate(sol))
+
+
+cdef class ExpExpr(UnaryExpr):
+
+    cpdef double _evaluate(self, Solution sol) except *:
+        return c_exp((<GenExpr>self.children[0])._evaluate(sol))
+
+
+cdef class LogExpr(UnaryExpr):
+
+    cpdef double _evaluate(self, Solution sol) except *:
+        return c_log((<GenExpr>self.children[0])._evaluate(sol))
+
+
+cdef class SqrtExpr(UnaryExpr):
+
+    cpdef double _evaluate(self, Solution sol) except *:
+        return c_sqrt((<GenExpr>self.children[0])._evaluate(sol))
+
+
+cdef class SinExpr(UnaryExpr):
+
+    cpdef double _evaluate(self, Solution sol) except *:
+        return c_sin((<GenExpr>self.children[0])._evaluate(sol))
+
+
+cdef class CosExpr(UnaryExpr):
+
     cpdef double _evaluate(self, Solution sol) except *:
-        cdef double res = (<GenExpr>self.children[0])._evaluate(sol)
-        return math.fabs(res) if self._op == "abs" else getattr(math, self._op)(res)
+        return c_cos((<GenExpr>self.children[0])._evaluate(sol))
 
 
 # class for constant expressions

src/pyscipopt/scip.pxd

@@ -2152,13 +2152,12 @@ cdef extern from "tpi/tpi.h":
 
 cdef class ExprLike:
 
+    cpdef double _evaluate(self, Solution sol)
     cdef ExprLike copy(self, bint copy=*)
 
 cdef class Expr(ExprLike):
     cdef public terms
 
-    cpdef double _evaluate(self, Solution sol)
-
 cdef class Event:
     cdef SCIP_EVENT* event
     # can be used to store problem data

src/pyscipopt/scip.pyi

@@ -342,12 +342,12 @@ class ExprLike:
     def __rtruediv__(self, other: object, /) -> GenExpr: ...
     def __neg__(self, /) -> Union[Expr, GenExpr]: ...
     def __pos__(self, /) -> Union[Expr, GenExpr]: ...
-    def __abs__(self) -> GenExpr: ...
-    def exp(self) -> GenExpr: ...
-    def log(self) -> GenExpr: ...
-    def sqrt(self) -> GenExpr: ...
-    def sin(self) -> GenExpr: ...
-    def cos(self) -> GenExpr: ...
+    def __abs__(self, /) -> AbsExpr: ...
+    def exp(self, /) -> ExpExpr: ...
+    def log(self, /) -> LogExpr: ...
+    def sqrt(self, /) -> SqrtExpr: ...
+    def sin(self, /) -> SinExpr: ...
+    def cos(self, /) -> CosExpr: ...
 
 @disjoint_base
 class Expr(ExprLike):
@@ -526,7 +526,7 @@ class MatrixConstraint(np.ndarray):
     def isStickingAtNode(self) -> Incomplete: ...
 
 class MatrixExpr(np.ndarray):
-    def _evaluate(self, sol: Incomplete) -> Incomplete: ...
+    def _evaluate(self, sol: Solution) -> Incomplete: ...
     def __array_ufunc__(
         self,
         ufunc: np.ufunc,
@@ -2241,7 +2241,13 @@ class Term:
 
 class UnaryExpr(GenExpr):
     def __init__(self, *args: Incomplete, **kwargs: Incomplete) -> None: ...
-    def __abs__(self) -> GenExpr: ...
+
+class AbsExpr(UnaryExpr): ...
+class ExpExpr(UnaryExpr): ...
+class LogExpr(UnaryExpr): ...
+class SqrtExpr(UnaryExpr): ...
+class SinExpr(UnaryExpr): ...
+class CosExpr(UnaryExpr): ...
 
 @disjoint_base
 class VarExpr(GenExpr):

tests/test_expr.py

@@ -212,8 +212,16 @@ def test_getVal_with_GenExpr():
     assert m.getVal(y / x) == 2
     # test "**(prod(1.0,**(sum(0.0,prod(1.0,x)),-1)),2)"
     assert m.getVal((1 / x) ** 2) == 1
-    # test "sin(sum(0.0,prod(1.0,x)))"
+
+    # test C-level math functions
+    assert m.getVal(abs(x)) == 1
+    assert m.getVal(abs(-x)) == 1
+    assert m.getVal(abs(abs(-x))) == 1
+    assert round(m.getVal(exp(x)), 6) == round(math.exp(1), 6)
+    assert round(m.getVal(log(x)), 6) == round(math.log(1), 6)
+    assert round(m.getVal(sqrt(x)), 6) == round(math.sqrt(1), 6)
     assert round(m.getVal(sin(x)), 6) == round(math.sin(1), 6)
+    assert round(m.getVal(cos(x)), 6) == round(math.cos(1), 6)
 
     with pytest.raises(TypeError):
         m.getVal(1)