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Reference Guide for OpenMatrix Language Functions
The Reference Guide contains documentation for all functions supported in the OpenMatrix language.
Elementary Math Commands
log1p
Natural logarithm of one plus the argument.

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- Extended Definitions for Advanced Users
  PDF file with in-depth information on key topics in the User's Guide.
- Scripting Guide for OpenMatrix Language
  OpenMatrix is a mathematical scripting language.
- Reference Guide for OpenMatrix Language Functions
  The Reference Guide contains documentation for all functions supported in the OpenMatrix language.
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    - abs
      Returns the absolute value of a scalar/matrix/complex number.
    - accumarray
      Array accumulation.
    - angle
      Returns the phase angle of z equal to atan2(imag(z), real(z)).
    - bi2de
      Converts numbers from binary or a specified base to their decimal equivalents.
    - bin2dec
      Converts binary numbers to their decimal equivalents.
    - cart2pol
      Converts Cartesian coordinates to polar or cylindrical.
    - cart2sph
      Converts Cartesian coordinates to spherical.
    - ceil
      Returns the smallest integer that is greater than or equal to x.
    - circshift
      Circular shift.
    - complex
      Returns a complex number composed of real elements.
    - conj
      Return the complex conjugate.
    - cplxpair
      Sorts x into its ascending pairs by real part.
    - cumprod
      The cumulative product of object's elements along a specified dimension.
    - cumsum
      The cumulative sum of an object's elements along a specified dimension.
    - de2bi
      Converts non-negative integers to their equivalents in binary or a specified base.
    - dec2bin
      Converts non-negative integers to their binary equivalents.
    - dec2hex
      Converts non-negative integers to their hexadecimal equivalents.
    - diag
      Creates a diagonal matrix or returns the diagonal elements of a matrix on diagonal k.
    - diff
      Returns a vector or matrix of differences.
    - double
      Converts A into double precision type.
    - e
      Symbol for the base of the natural logarithm.
    - eps
      The spacing between two adjacent numbers in a given machine's floating point system, Epsilon.
    - exp
      For each element of x, returns e^x.
    - expm1
      Exponential of the argument, minus one.
    - eye
      Returns an identity matrix.
    - factor
      Returns the prime factorization of X. If two outputs are requested, returns the unique primes of X.
    - find
      Returns the position of non-zero elements in a matrix.
    - fix
      Rounds X down to zero.
    - flip
      Returns R, which is the matrix, m, flipped along the axis, a.
    - fliplr
      Returns R, which is the matrix, m, with its columns flipped left to right.
    - flipud
      Returns R, which is the matrix, m, with its rows flipped from top to bottom.
    - floor
      Returns the largest integer that is not greater than x.
    - gcd
      Returns the greatest common deviser of the set x.
    - hex2dec
      Converts hexadecimal numbers to their decimal equivalents.
    - i
      The imaginary number i, such that i^2 = -1
    - imag
      Returns the imaginary component of a complex number.
    - ind2sub
      Returns subscript from the linear index ind.
    - intersect
      Returns the elements that are common to two sets, without duplication.
    - ipermute
      Generalized reversing transpose of a matrix, using a permutation vector.
    - isbool
      Determines if x is a logical value.
    - iscomplex
      Determines if x is a complex value.
    - isempty
      Determines if x is an empty value.
    - isequal
      Compares x1,x2,... to each other; if all are equal, returns boolean value true, otherwise returns false.
    - isglobal
      Returns a logical value indicating whether the input is global in scope.
    - islogical
      Determines if x is a logical value.
    - ismember
      Determine which elements of the first argument exist in the second argument.
    - isprime
      Determines if x is a prime number.
    - isreal
      Determines if x is a real number.
    - issorted
      Returns true if the array x sorted by mode. By default mode is ascending.
    - isvector
      Determines if x is a vector.
    - j
      The imaginary number i, such that i^2 = -1.
    - lcm
      Least common multiple.
    - length
      Returns the length of an object's largest dimension.
    - log
      Computes the natural log for each element of x.
    - log1p
      Natural logarithm of one plus the argument.
    - log2
      Computes the base-2 logarithm of a matrix.
    - log10
      Computes the base-10 logarithm for each element of x.
    - logical
      Converts x to a logical type.
    - max
      Returns maximum values.
    - min
      Returns minimum values.
    - mod
      Returns x modulo y.
    - ndims
      Returns the number of dimensions of an array.
    - nextpow2
      Computes the exponent of the smallest power of 2 that is greater than or equal to the input in magnitude.
    - numel
      Returns the number of elements in x.
    - ones
      Returns a matrix of ones.
    - permute
      Generalized transpose of a matrix, using a permutation vector.
    - pi
      Symbol for pi.
    - pol2cart
      Converts polar or cylindrical coordinates to Cartesian.
    - pow2
      Computes powers of 2.
    - primes
      Returns all primes up to X.
    - prod
      Returns vector or matrix element products.
    - rank
      Computes the rank of matrix A.
    - rat
      Returns a rational approximation of the input using a continued fraction approximation.
    - real
      Returns the real part of x.
    - realmax
      Returns a matrix whose elements are all the largest floating point number that is representable.
    - realmin
      Returns a matrix whose elements are all the smallest normalized floating point number that is representable.
    - rem
      The resulting remainder of x / y.
    - repmat
      Replicates an input to create a block matrix with the number of specified replications in each dimension.
    - reshape
      Returns a matrix with the same elements as the input, but with reassigned dimensions.
    - rot90
      Returns R, the result of rotating matrix, m, in 90-degree succession(s).
    - round
      Rounds values to specified precision.
    - setdiff
      Returns the subset of the first set that does not belong to the second set.
    - setxor
      Returns the elements contained in either of two sets, but not in their intersection.
    - shiftdim
      Shift dimensions.
    - sign
      Returns the sign of the value passed in.
    - single
      Marks the given input in as a single precision data type. Single precision data can be used in the save command to write with single precision in .mat files.
    - size
      Returns the size of each dimension of an object.
    - sph2cart
      Converts spherical coordinates to Cartesian.
    - sqrt
      Returns the square root of each element of x.
    - squeeze
      Removes singular dimensions from a matrix.
    - sub2ind
      Converts subscript to a linear index.
    - sum
      Returns vector or matrix element sums.
    - union
      Returns the elements contained in either of two sets, without duplication.
    - unique
      Returns the elements of a set, without duplication.
    - vec2mat
      Converts a vector, v, to a matrix with the specified number of columns, c.
    - zeros
      Creates a matrix of zeros.
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  Key terms associated with the software.
Frequently Asked Questions
You've got questions? We've got answers!

log1p

Natural logarithm of one plus the argument.

Syntax

R = log1p(x)

Inputs

x: Type: double | complex; Dimension: scalar | vector | matrix

Outputs

R: The returned values.; Type: double | complex; Dimension: scalar | vector | matrix.

Example

Show that log1p(x + 1) has better accuracy than log(x) for small real values of x

x = 1e-18;
a = log(x+1)

a = 0

b = log1p(x)

b = 1e-18

The value of a has lost precision, but b has not.