+=head2 Quasi Affine Expressions
+
+The zero quasi affine expression can be created using
+
+ __isl_give isl_aff *isl_aff_zero(
+ __isl_take isl_local_space *ls);
+
+Quasi affine expressions can be copied and free using
+
+ #include <isl/aff.h>
+ __isl_give isl_aff *isl_aff_copy(__isl_keep isl_aff *aff);
+ void *isl_aff_free(__isl_take isl_aff *aff);
+
+A (rational) bound on a dimension can be extracted from an C<isl_constraint>
+using the following function. The constraint is required to have
+a non-zero coefficient for the specified dimension.
+
+ #include <isl/constraint.h>
+ __isl_give isl_aff *isl_constraint_get_bound(
+ __isl_keep isl_constraint *constraint,
+ enum isl_dim_type type, int pos);
+
+Conversely, an equality constraint equating
+the affine expression to zero or an inequality constraint enforcing
+the affine expression to be non-negative, can be constructed using
+
+ __isl_give isl_constraint *isl_equality_from_aff(
+ __isl_take isl_aff *aff);
+ __isl_give isl_constraint *isl_inequality_from_aff(
+ __isl_take isl_aff *aff);
+
+The expression can be inspected using
+
+ #include <isl/aff.h>
+ isl_ctx *isl_aff_get_ctx(__isl_keep isl_aff *aff);
+ int isl_aff_dim(__isl_keep isl_aff *aff,
+ enum isl_dim_type type);
+ __isl_give isl_local_space *isl_aff_get_local_space(
+ __isl_keep isl_aff *aff);
+ const char *isl_aff_get_dim_name(__isl_keep isl_aff *aff,
+ enum isl_dim_type type, unsigned pos);
+ int isl_aff_get_constant(__isl_keep isl_aff *aff,
+ isl_int *v);
+ int isl_aff_get_coefficient(__isl_keep isl_aff *aff,
+ enum isl_dim_type type, int pos, isl_int *v);
+ int isl_aff_get_denominator(__isl_keep isl_aff *aff,
+ isl_int *v);
+ __isl_give isl_div *isl_aff_get_div(
+ __isl_keep isl_aff *aff, int pos);
+
+It can be modified using
+
+ #include <isl/aff.h>
+ __isl_give isl_aff *isl_aff_set_constant(
+ __isl_take isl_aff *aff, isl_int v);
+ __isl_give isl_aff *isl_aff_set_constant_si(
+ __isl_take isl_aff *aff, int v);
+ __isl_give isl_aff *isl_aff_set_coefficient(
+ __isl_take isl_aff *aff,
+ enum isl_dim_type type, int pos, isl_int v);
+ __isl_give isl_aff *isl_aff_set_coefficient_si(
+ __isl_take isl_aff *aff,
+ enum isl_dim_type type, int pos, int v);
+ __isl_give isl_aff *isl_aff_set_denominator(
+ __isl_take isl_aff *aff, isl_int v);
+
+ __isl_give isl_aff *isl_aff_add_constant(
+ __isl_take isl_aff *aff, isl_int v);
+ __isl_give isl_aff *isl_aff_add_coefficient_si(
+ __isl_take isl_aff *aff,
+ enum isl_dim_type type, int pos, int v);
+
+Note that the C<set_constant> and C<set_coefficient> functions
+set the I<numerator> of the constant or coefficient, while
+C<add_constant> and C<add_coefficient> add an integer value to
+the possibly rational constant or coefficient.
+
+Operations include
+
+ #include <isl/aff.h>
+ __isl_give isl_aff *isl_aff_add(__isl_take isl_aff *aff1,
+ __isl_take isl_aff *aff2);
+ __isl_give isl_aff *isl_aff_sub(__isl_take isl_aff *aff1,
+ __isl_take isl_aff *aff2);
+ __isl_give isl_aff *isl_aff_neg(__isl_take isl_aff *aff);
+ __isl_give isl_aff *isl_aff_ceil(__isl_take isl_aff *aff);
+ __isl_give isl_aff *isl_aff_scale(__isl_take isl_aff *aff,
+ isl_int f);
+ __isl_give isl_aff *isl_aff_scale_down(__isl_take isl_aff *aff,
+ isl_int f);
+
+An expression can be printed using
+
+ #include <isl/aff.h>
+ __isl_give isl_printer *isl_printer_print_aff(
+ __isl_take isl_printer *p, __isl_keep isl_aff *aff);
+