R8LIB
A Double Precision Real Arithmetic Utility Library

R8LIB is a Python library which contains a number of utilities for double precision real (R8) arithmetic.

Licensing:

The computer code and data files made available on this web page are distributed under the GNU LGPL license.

Languages:

R8LIB is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version and a Python version.

Related Programs:

C4LIB, a Python library which contains many utility routines, using "C4" or "single precision complex" arithmetic.

C8LIB, a Python library which contains many utility routines, using "C8" or "double precision complex" arithmetic.

I4LIB, a PYTHON library which contains many utility routines, using "I4" or "single precision integer" arithmetic.

R4LIB, a Python library which contains many utility routines using single precision real (R4) arithmetic.

UNIFORM, a Python library which contains uniform random number generators (RNG's) for several arithmetic types.

References:

1. Thomas Cormen, Charles Leiserson, Ronald Rivest,
   Introduction to Algorithms,
   MIT Press, 2001,
   ISBN: 0262032937,
   LC: QA76.C662.
2. Albert Nijenhuis, Herbert Wilf,
   Combinatorial Algorithms for Computers and Calculators,
   Second Edition,
   Academic Press, 1978,
   ISBN: 0-12-519260-6,
   LC: QA164.N54.

Source Code:

• agm_values.py, returns selected values of the arithmetic geometric mean;
• gamma_values.py, returns selected values of the gamma function;
• gamma_log_values.py, returns selected values of the log(gamma) function;
• i4_log_10.py, returns the integer part of the logarithm base 10 of ABS(X);
• i4_sign.py, returns the sign of an I4.
• i4_uniform_ab.py, returns a random I4 between A and B.
• i4vec_indicator0.py, returns an indicator vector as an I4VEC.
• i4vec_indicator1.py, returns an indicator vector as an I4VEC.
• i4vec_print.py, prints an I4VEC.
• i4vec_transpose_print.py, prints the transpose of an I4VEC.
• perm0_check.py, checks a permutation of ( 0,...,N-1).
• perm0_uniform.py, randomly selects a checks a permutation of ( 0,...,N-1).
• perm1_check.py, checks a checks a permutation of ( 1,...,N).
• perm1_uniform.py, randomly selects a permutation of ( 1,...,N).
• r8_abs.py, returns the absolute value of an R8.
• r8_acos.py, returns the arc-cosine of an R8.
• r8_acosh.py, returns the arc-hyperbolic cosine of an R8.
• r8_add.py, adds two R8's.
• r8_agm.py, computes the arithmetic-geometry mean of two R8's.
• r8_aint.py, truncates an R8 to an integer value.
• r8_asin.py, returns the arc-sine of an R8.
• r8_asinh.py, computes the inverse hyperbolic sine;
• r8_atan.py, returns the arc-tangent of an R8.
• r8_atanh.py, computes the inverse hyperbolic tangent;
• r8_big.py, returns a "big" R8;
• r8_cas.py, returns the "casine" of an R8.
• r8_ceiling.py, rounds an R8 up to the nearest integer.
• r8_choose.py, returns the combinatorial coefficient C(N,K).
• r8_chop.py, chops an R8 to a given number of binary places.
• r8_cosd.py, returns the cosine of an angle in degrees.
• r8_cotd.py, returns the cotangent of an angle in degrees.
• r8_csc.py, returns the cosecant of an R8.
• r8_cscd.py, returns the cosecant of an angle in degrees.
• r8_cube_root.py, returns the cube root of an R8.
• r8_degrees.py, converts a measurement from radians to degrees.
• r8_diff.py, computes (X-Y) to a specified accuracy.
• r8_digit.py, returns a particular decimal digit of an R8.
• r8_divide_i4.py, returns an I4 fraction as an R8.
• r8_e.py, returns the natural logarithm base as an R8.
• r8_epsilon.py, returns the R8 roundoff unit.
• r8_epsilon_compute.py, computes the R8 roundoff unit.
• r8_exp.py, evaluates the exponential function, while avoiding underflow and overflow.
• r8_factorial.py, evaluates the factorial function.
• r8_factorial_values.py returns values of the real factorial function.
• r8_factorial2.py, evaluates the double factorial function.
• r8_factorial2_values.py returns values of the double factorial function.
• r8_fall.py, evaluates the falling factorial function of an R8.
• r8_fall_values.py, returns selected values of the falling factorial.
• r8_floor.py, rounds an R8 "down" (towards -oo) to the next integer.
• r8_fraction.py, uses real arithmetic on an integer ratio.
• r8_fractional.py, returns the fractional part of an R8.
• r8_gamma.py, returns the gamma function of an R8.
• r8_gamma_log.py, returns the logarithm of the gamma function of an R8.
• r8_huge.py, returns a "huge" R8;
• r8_hypot.py, returns sqrt ( x^2 + y^2 );
• r8_in_01.py, is true if the value is in [0,1];
• r8_insignificant.py, is true if an R8 is insignificant;
• r8_is_int.py, is true if an R8 equals an integer value;
• r8_log_2.py, returns the logarithm base 2 of the absolute value of an R8;
• r8_log_10.py, returns the logarithm base 10 of the absolute value of an R8;
• r8_log_b.py, returns the logarithm base B of the absolute value of an R8;
• r8_mant.py, returns the mantissa of an R8;
• r8_max.py, returns the maximum of two R8's;
• r8_min.py, returns the minimum of two R8's;
• r8_mod.py, returns the remainder of real division;
• r8_modp.py, returns the nonnegative remainder of real division;
• r8_mop.py, returns a power of -1 as an R8;
• r8_normal_01.py, returns a unit pseudonormal R8;
• r8_normal_ab.py, returns a pseudonormal R8 with mean A and variance B.
• r8_pi.py, returns the value of Pi.
• r8_pi_sqrt.py, returns the value of the square root of Pi.
• r8_power.py, returns the value of an integral power of an R8;
• r8_power_fast.py, quickly returns the value of an integral power of an R8;
• r8_print.py, prints an R8;
• r8_pythag.py, computes sqrt ( A^2 + B^2 ) avoiding unnecessary overflow and underflow;
• r8_radians.py, converts a measurement from degrees to radians.
• r8_rise.py, computes a rising factorial as an R8;
• r8_rise_values.py, returns selected values of the rising factorial.
• r8_round.py, rounds an R8 to the nearest integral value.
• r8_round_i4.py, rounds an R8 to the nearest integral value, returned as an I4.
• r8_round2.py, rounds an R8 to a specified number of binary digits.
• r8_roundb.py, rounds an R8 to a specified number of digits in a given base.
• r8_roundx.py, rounds an R8 to a specified number of decimal digits.
• r8_secd.py, returns the secant of an angle in degrees.
• r8_sech.py, evaluates the hyperbolic secant of an R8.
• r8_sign.py, returns the sign of an R8.
• r8_sign3.py, returns the three-way sign of an R8.
• r8_sign_char.py, returns a character indicating the sign of an R8.
• r8_sign_match.py, is TRUE if two R8's have the same sign.
• r8_sign_match_strict.py, is TRUE if two R8's have the same strict sign.
• r8_sign_opposite.py, is TRUE if two R8's have opposite sign.
• r8_sign_opposite_strict.py, is TRUE if two R8's have strictly opposite signs.
• r8_sind.py, returns the sine of an angle in degrees.
• r8_sqrt_i4.py, returns the square root of an I4 as an R8.
• r8_swap.py, swaps two R8's.
• r8_swap3.py, swaps three R8's.
• r8_tand.py, returns the tangent of an angle in degrees.
• r8_tiny.py, returns a "tiny" R8.
• r8_to_dhms.py, converts decimal days into days, hours, minutes, seconds.
• r8_to_i4.py, maps X in [XMIN,XMAX] to I in [IMIN,IMAX];
• r8_to_r8_discrete.py, maps R to RD in [RMIN, RMAX] with NR possible values.
• r8_uniform_01.py, returns a unit pseudorandom R8.
• r8_uniform_ab.py, returns a scaled pseudorandom R8.
• r8_unswap3.py, unswaps 3 R8's.
• r8_walsh_1d.py, evaluates the Walsh function;
• r8_wrap.py, forces an R8 to lie between given limits by wrapping.
• r82col_print_part.py, prints part of an (N,2) array of data.
• r82row_print_part.py, prints part of a (2,N) array of data.
• r83col_print_part.py, prints part of an (N,3) array of data.
• r83row_print_part.py, prints part of a (3,N) array of data.
• r8col_swap.py, swaps two columns of an R8COL.
• r8mat_house_form.py, constructs a Householder matrix from its compact form;
• r8mat_indicator.py, returns an indicator R8MAT.
• r8mat_mm.py, computes a matrix-matrix product.
• r8mat_mmt.py, computes a matrix-transpose(matrix) product.
• r8mat_mtm.py, computes a (transposed matrix)-matrix product.
• r8mat_mtv.py, computes the product of a transposed R8MAT times an R8VEC.
• r8mat_mv.py, computes the product of an R8MAT times an R8VEC.
• r8mat_nint.py, rounds the entries of an R8MAT.
• r8mat_nonzeros.py, returns the number of nonzeros in an R8MAT.
• r8mat_norm_fro.py, returns the Frobenius norm of an R8MAT.
• r8mat_norm_l1.py, returns the L1 norm of an R8MAT.
• r8mat_norm_li.py, returns the Loo norm of an R8MAT.
• r8mat_print.py, prints an R8MAT.
• r8mat_print_some.py, prints some of an R8MAT.
• r8mat_sub.py, subtracts one R8MAT from another.
• r8mat_transpose.py, transposes an R8MAT.
• r8mat_transpose_print.py, prints an R8MAT, transposed.
• r8mat_transpose_print_some.py, prints some of an R8MAT, transposed.
• r8mat_uniform_01.py, returns a unit pseudorandom R8MAT.
• r8mat_uniform_ab.py, returns a scaled pseudorandom R8MAT.
• r8poly_degree.py returns the degree of an R8POLY.
• r8poly_print.py, prints a polynomial;
• r8poly_value_horner.py, evaluates a polynomial using Horner's method;
• r8vec_amax.py, returns the maximum absolute value entry in an R8VEC.
• r8vec_amin.py, returns the minimum absolute value entry in an R8VEC.
• r8vec_asum.py, sums the absolute values of the entries in an R8VEC.
• r8vec_concatenate.py, concatenates two R8VECs.
• r8vec_copy.py, copies an R8VEC.
• r8vec_direct_product.py, creates a direct product of R8VEC's.
• r8vec_house_column.py, defines a Householder premultiplier that packs a column.
• r8vec_indicator0.py, evaluates the 0-based indicator vector (0,1,2,...) as an R8VEC.
• r8vec_indicator1.py, evaluates the 1-based indicator vector (1,2,3,...) as an R8VEC.
• r8vec_linspace.py, returns an R8VEC of values evenly spaced between given limits.
• r8vec_max.py, returns the maximum entry in an R8VEC.
• r8vec_min.py, returns the minimum entry in an R8VEC.
• r8vec_nint.py, rounds an R8VEC.
• r8vec_norm_l0.py, computes the L0 "norm" of an R8VEC.
• r8vec_norm_l2.py, computes the L2 norm of an R8VEC.
• r8vec_norm_li.py, computes the Loo norm of an R8VEC.
• r8vec_permute.py, permutes an R8VEC.
• r8vec_print.py, prints an R8VEC.
• r8vec_product.py, computes the product of the entries in an R8VEC.
• r8vec_step.py, evaluates a unit step function.
• r8vec_sum.py, sums the entries in an R8VEC.
• r8vec_uniform_01.py, returns a unit pseudorandom R8VEC.
• r8vec_uniform_ab.py, returns a scaled pseudorandom R8VEC.
• roots_to_r8poly.py, takes a set of N real roots and determines the N+1 coefficients of the corresponding polynomial.
• timestamp.py, prints the current YMDHMS date as a timestamp.

Examples and Tests:

• r8lib_test.py, a program that calls all the tests.
• r8lib_test.sh, a BASH shell script that executes the test program.
• r8lib_test_output.txt, the output file.

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