bc: Special Expressions

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1 3.6 Special Expressions
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1 There are a few more special expressions that are provided in 'bc'.
1 These have to do with user-defined functions and standard functions.
1 They all appear as "NAME'('PARAMETERS')'".  ⇒Functions, for
1 user-defined functions.  The standard functions are:
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1 'length ( EXPRESSION )'
1      The value of the length function is the number of significant
1      digits in the expression.
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1 'read ( )'
1      The 'read' function (an extension) will read a number from the
1      standard input, regardless of where the function occurs.  Beware,
1      this can cause problems with the mixing of data and program in the
1      standard input.  The best use for this function is in a previously
1      written program that needs input from the user, but never allows
1      program code to be input from the user.  The value of the 'read'
1      function is the number read from the standard input using the
1      current value of the variable IBASE for the conversion base.
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1 'scale ( EXPRESSION )'
1      The value of the 'scale' function is the number of digits after the
1      decimal point in the expression.
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1 'sqrt ( EXPRESSION )'
1      The value of the 'sqrt' function is the square root of the
1      expression.  If the expression is negative, a run time error is
1      generated.
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