+=head2 Values
+
+An C<isl_val> represents an integer value, a rational value
+or one of three special values, infinity, negative infinity and NaN.
+Some predefined values can be created using the following functions.
+
+ #include <isl/val.h>
+ __isl_give isl_val *isl_val_zero(isl_ctx *ctx);
+ __isl_give isl_val *isl_val_one(isl_ctx *ctx);
+ __isl_give isl_val *isl_val_nan(isl_ctx *ctx);
+ __isl_give isl_val *isl_val_infty(isl_ctx *ctx);
+ __isl_give isl_val *isl_val_neginfty(isl_ctx *ctx);
+
+Specific integer values can be created using the following functions.
+
+ #include <isl/val.h>
+ __isl_give isl_val *isl_val_int_from_si(isl_ctx *ctx,
+ long i);
+ __isl_give isl_val *isl_val_int_from_ui(isl_ctx *ctx,
+ unsigned long u);
+
+They can be copied and freed using the following functions.
+
+ #include <isl/val.h>
+ __isl_give isl_val *isl_val_copy(__isl_keep isl_val *v);
+ void *isl_val_free(__isl_take isl_val *v);
+
+They can be inspected using the following functions.
+
+ #include <isl/val.h>
+ isl_ctx *isl_val_get_ctx(__isl_keep isl_val *val);
+ long isl_val_get_num_si(__isl_keep isl_val *v);
+ long isl_val_get_den_si(__isl_keep isl_val *v);
+ double isl_val_get_d(__isl_keep isl_val *v);
+
+Note that C<isl_val_get_num_si>, C<isl_val_get_den_si> and
+C<isl_val_get_d> can only be applied to rational values.
+
+An C<isl_val> can be modified using the following function.
+
+ #include <isl/val.h>
+ __isl_give isl_val *isl_val_set_si(__isl_take isl_val *v,
+ long i);
+
+The following unary properties are defined on C<isl_val>s.
+
+ #include <isl/val.h>
+ int isl_val_sgn(__isl_keep isl_val *v);
+ int isl_val_is_zero(__isl_keep isl_val *v);
+ int isl_val_is_one(__isl_keep isl_val *v);
+ int isl_val_is_negone(__isl_keep isl_val *v);
+ int isl_val_is_nonneg(__isl_keep isl_val *v);
+ int isl_val_is_nonpos(__isl_keep isl_val *v);
+ int isl_val_is_pos(__isl_keep isl_val *v);
+ int isl_val_is_neg(__isl_keep isl_val *v);
+ int isl_val_is_int(__isl_keep isl_val *v);
+ int isl_val_is_rat(__isl_keep isl_val *v);
+ int isl_val_is_nan(__isl_keep isl_val *v);
+ int isl_val_is_infty(__isl_keep isl_val *v);
+ int isl_val_is_neginfty(__isl_keep isl_val *v);
+
+Note that the sign of NaN is undefined.
+
+The following binary properties are defined on pairs of C<isl_val>s.
+
+ #include <isl/val.h>
+ int isl_val_lt(__isl_keep isl_val *v1,
+ __isl_keep isl_val *v2);
+ int isl_val_le(__isl_keep isl_val *v1,
+ __isl_keep isl_val *v2);
+ int isl_val_gt(__isl_keep isl_val *v1,
+ __isl_keep isl_val *v2);
+ int isl_val_ge(__isl_keep isl_val *v1,
+ __isl_keep isl_val *v2);
+ int isl_val_eq(__isl_keep isl_val *v1,
+ __isl_keep isl_val *v2);
+ int isl_val_ne(__isl_keep isl_val *v1,
+ __isl_keep isl_val *v2);
+
+For integer C<isl_val>s we additionally have the following binary property.
+
+ #include <isl/val.h>
+ int isl_val_is_divisible_by(__isl_keep isl_val *v1,
+ __isl_keep isl_val *v2);
+
+An C<isl_val> can also be compared to an integer using the following
+function. The result is undefined for NaN.
+
+ #include <isl/val.h>
+ int isl_val_cmp_si(__isl_keep isl_val *v, long i);
+
+The following unary operations are available on C<isl_val>s.
+
+ #include <isl/val.h>
+ __isl_give isl_val *isl_val_abs(__isl_take isl_val *v);
+ __isl_give isl_val *isl_val_neg(__isl_take isl_val *v);
+ __isl_give isl_val *isl_val_floor(__isl_take isl_val *v);
+ __isl_give isl_val *isl_val_ceil(__isl_take isl_val *v);
+ __isl_give isl_val *isl_val_trunc(__isl_take isl_val *v);
+
+The following binary operations are available on C<isl_val>s.
+
+ #include <isl/val.h>
+ __isl_give isl_val *isl_val_abs(__isl_take isl_val *v);
+ __isl_give isl_val *isl_val_neg(__isl_take isl_val *v);
+ __isl_give isl_val *isl_val_floor(__isl_take isl_val *v);
+ __isl_give isl_val *isl_val_ceil(__isl_take isl_val *v);
+ __isl_give isl_val *isl_val_trunc(__isl_take isl_val *v);
+ __isl_give isl_val *isl_val_2exp(__isl_take isl_val *v);
+ __isl_give isl_val *isl_val_min(__isl_take isl_val *v1,
+ __isl_take isl_val *v2);
+ __isl_give isl_val *isl_val_max(__isl_take isl_val *v1,
+ __isl_take isl_val *v2);
+ __isl_give isl_val *isl_val_add(__isl_take isl_val *v1,
+ __isl_take isl_val *v2);
+ __isl_give isl_val *isl_val_add_ui(__isl_take isl_val *v1,
+ unsigned long v2);
+ __isl_give isl_val *isl_val_sub(__isl_take isl_val *v1,
+ __isl_take isl_val *v2);
+ __isl_give isl_val *isl_val_sub_ui(__isl_take isl_val *v1,
+ unsigned long v2);
+ __isl_give isl_val *isl_val_mul(__isl_take isl_val *v1,
+ __isl_take isl_val *v2);
+ __isl_give isl_val *isl_val_mul_ui(__isl_take isl_val *v1,
+ unsigned long v2);
+ __isl_give isl_val *isl_val_div(__isl_take isl_val *v1,
+ __isl_take isl_val *v2);
+
+On integer values, we additionally have the following operations.
+
+ #include <isl/val.h>
+ __isl_give isl_val *isl_val_2exp(__isl_take isl_val *v);
+ __isl_give isl_val *isl_val_mod(__isl_take isl_val *v1,
+ __isl_take isl_val *v2);
+ __isl_give isl_val *isl_val_gcd(__isl_take isl_val *v1,
+ __isl_take isl_val *v2);
+ __isl_give isl_val *isl_val_gcdext(__isl_take isl_val *v1,
+ __isl_take isl_val *v2, __isl_give isl_val **x,
+ __isl_give isl_val **y);
+
+The function C<isl_val_gcdext> returns the greatest common divisor g
+of C<v1> and C<v2> as well as two integers C<*x> and C<*y> such
+that C<*x> * C<v1> + C<*y> * C<v2> = g.
+
+A value can be read from input using
+
+ #include <isl/val.h>
+ __isl_give isl_val *isl_val_read_from_str(isl_ctx *ctx,
+ const char *str);
+
+A value can be printed using
+
+ #include <isl/val.h>
+ __isl_give isl_printer *isl_printer_print_val(
+ __isl_take isl_printer *p, __isl_keep isl_val *v);
+
+=head3 GMP specific functions
+
+These functions are only available if C<isl> has been compiled with C<GMP>
+support.
+
+Specific integer and rational values can be created from C<GMP> values using
+the following functions.
+
+ #include <isl/val_gmp.h>
+ __isl_give isl_val *isl_val_int_from_gmp(isl_ctx *ctx,
+ mpz_t z);
+ __isl_give isl_val *isl_val_from_gmp(isl_ctx *ctx,
+ const mpz_t n, const mpz_t d);
+
+The numerator and denominator of a rational value can be extracted as
+C<GMP> values using the following functions.
+
+ #include <isl/val_gmp.h>
+ int isl_val_get_num_gmp(__isl_keep isl_val *v, mpz_t z);
+ int isl_val_get_den_gmp(__isl_keep isl_val *v, mpz_t z);
+
+=head2 Integers (obsolescent)