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Reference Guide for OpenMatrix Language Functions
The Reference Guide contains documentation for all functions supported in the OpenMatrix language.
String Operations Commands
isletter
Returns a boolean, logical matrix or cell array, whose values are true if the corresponding elements of the input are letters and false, if otherwise.

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Reference Guides
Explore the Extended Definitions, OML Guides, Block Library, API Guide and Glossary.
- 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.
  - ABF Commands
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  - String Operations Commands
    - blanks
      Returns a string which consists of n spaces.
    - cellstr
      Convert a character vector, s, to a cell array, R.
    - char
      Returns a string matrix whose elements are the input arguments, vertically concatenated.
    - contains
      Searches for pattern, pat, in the input, src, and returns true if pat is found.
    - deblank
      Trims trailing whitespaces from strings, matrices and cell arrays. For matrices, trailing whitespaces are stripped from each row to the size of the longest string in the matrix, to make the length of each row consistent.
    - func2str
      Returns a string containing the name of the functionf.
    - ischar
      Returns true if the input, s, is a string and false otherwise.
    - isgraph
      Returns a boolean, logical matrix or cell array, whose values are true if the corresponding elements of the input are printable characters excluding spaces and false otherwise.
    - isletter
      Returns a boolean, logical matrix or cell array, whose values are true if the corresponding elements of the input are letters and false, if otherwise.
    - isprint
      Returns a boolean, logical matrix or cell array, whose values are true if the corresponding elements of the input are printable characters including spaces and false otherwise.
    - isspace
      Returns a boolean, logical matrix or cell array, whose values are true if the corresponding elements of the input are whitespaces and false, if otherwise.
    - isstr
      Returns true if the input, s, is a string and false otherwise.
    - lower
      Returns a string or cell array where each uppercase character of the input string, matrix or cell array is replaced by the corresponding lowercase character. Non-alphabetic characters in the input are not modified.
    - mat2str
      Writes the values of a 2D matrix, m, to a string, R.
    - num2str
      Returns a string or a string array after converting the input x. Input x can be a scalar, complex number, or matrix. Optional arguments, precision, can be used to format the output, R, by specifying the number of significant digits. Valid values of R are positive integers.
    - regexp
      Returns the results after searching for the regular expression or pattern, pattern, in the input, s.
    - regexprep
      Returns the result after replacing the regular expression, pat with rep in the input, src.
    - sprintf
      Returns a formatted string, based on the format, strformat specified.
    - sscanf
      Returns result R after reading a formatted string s, specified by template t.
    - str2double
      Returns a scalar, complex number or matrix, R, after converting the input s.
    - str2func
      Returns the function handle corresponding to the input string argument s. If an optional second argument called global is given, only global functions are included in the scope of the lookup.
    - str2mat
      Returns a string matrix, R, whose elements are inputs, s, vertically concatenated. Strings that form the rows R are padded with spaces so that R is valid.
    - str2num
      Returns a scalar, complex number or matrix, R, after converting the input s.
    - strcat
      Concatenates inputs s, ... and returns the result, R, which is of type string or cell array.
    - strcmp
      Performs a case-sensitive comparison of x1 with x2. Returns 1 if the characters compared are identical and 0 otherwise.
    - strcmpi
      Performs a case-insensitive comparison of x1 with x2. Returns 1 if the characters compared are identical and 0 otherwise.
    - strfind
      Searches for all instances of the pattern pat in s. Returns a matrix, R, whose elements are indices of occurrences of pat in s.
    - strip
      Trims leading and trailing characters from strings.
    - strjoin
      Returns a string, R, which is the result of concatenating the elements of the cell array of strings, c, with each element separated by the delimiter delim. Delimiter delim is optional and if no value is specified, whitespace is used.
    - strncmp
      Performs a case-sensitive comparison of the first n characters of x1 with x2. Returns 1 if the characters compared are identical and 0 otherwise.
    - strncmpi
      Performs a case-insensitive comparison of the first n characters of x1 with x2. Returns 1 if the characters compared are identical and 0 otherwise.
    - strrep
      Searches and replaces all instances of the pattern pat in s with the new pattern newpat. The output R will be a string or a cell of strings, based on the type of s.
    - strsplit
      Tokenizes the string s with the given delimiter delim.
    - strtok
      Splits the string s at the given delimiter delim and returns a cell array whose elements are the substrings of string s.
    - strtrim
      Trims leading and trailing whitespaces from strings, matrices and cell arrays. For matrices, leading and trailing whitespaces are stripped from each row to the size of the longest string in the matrix, to make the length of each row consistent.
    - strvcat
      Returns a string matrix whose elements are the input arguments, vertically concatenated.
    - toascii
      Converts every character in the string, s, to its ASCII equivalent.
    - tolower
      Returns a string or cell array where each uppercase character of the input string, matrix or cell array is replaced by the corresponding lowercase character. Non-alphabetic characters in the input are not modified.
    - toupper
      Returns a string or cell array where each lowercase character of the input string, matrix or cell array is replaced by the corresponding uppercase character. Non-alphabetic characters in the input are not modified.
    - upper
      Returns a string or cell array where each lowercase character of the input string, matrix or cell array is replaced by the corresponding uppercase character. Non-alphabetic characters in the input are not modified.
  - System Commands
  - Table Commands
  - Time Commands
  - Trigonometry Commands
  - OML to Python Bridge Commands
  - Python to OML Bridge Commands
- Block Reference Guide
  Describes all of the blocks in the installed Twin Activate library.
- Function Guide for Twin Activate
  Provides information about developing and simulating models through the Twin Activate Application Program Interface.
- Glossary
  Key terms associated with the software.
Frequently Asked Questions
You've got questions? We've got answers!

isletter

Returns a boolean, logical matrix or cell array, whose values are true if the corresponding elements of the input are letters and false, if otherwise.

Syntax

R = isletter(s)

Inputs

s: Type: Any finite scalar | string | mat | cell

Outputs

R: Type: logical | mat | cell

Examples

String input:

R = isletter('test123')
R = [Matrix] 1 x 7
1  1  1  1  0  0  0

Cell array input:

R = isletter({23, 'test123'})
R =
{
[1,1] 0
[1,2] [Matrix] 1 x 7
1  1  1  1  0  0  0
}