RCALC(1)						      General Commands Manual							  RCALC(1)

NAME

       rcalc - record calculator

SYNOPSIS

       rcalc [ -b ][ -l ][ -p ][ -n ][ -w ][ -u ][ -tS ][ -i format ][ -o format ][ -f source ][ -e expr ][ -s svar=sval ] file ..

DESCRIPTION

       Rcalc transforms ``records'' from each file according to the given set of literal and relational information.  By default, records are sep-
       arated by newlines, and contain numeric fields separated by tabs.  The -tS option is used to specify an alternate tab character.

       A -i format option specifies a template for an alternate input record format.  Format is interpreted as a specification string if  it  con-
       tains a dollar sign '$'.  Otherwise, it is interpreted as the name of the file containing the format specification.  In either case, if the
       format does not end with a newline, one will be added automatically.  A special form of the -i option may be followed immediately by a  'd'
       or  an  'f'  and  an  optional count, which defaults to 1, indicating the number of double or float binary values to read per record on the
       input file.  If the input is byte-swapped, the -iD or -iF options may be substituted.  If binary input is specified, no	format	string	or
       file is needed.

       A -o format option specifies an alternate output record format.	It is interpreted the same as an input specification, except that the spe-
       cial -od or -of options do not require a count, as this will be determined by the number of output channels in the given  expressions.	If
       byte-swapped output is desired, the -oD or -oF options may be substituted.

       The  -p	option	specifies  "passive  mode,"  where characters that do not match the input format are passed unaltered to the output.  This
       option has no effect unless -i is also specified, and does not make much sense unless -o is also given.	With both input  and  output  for-
       mats, the passive mode can effectively substitute information in the middle of a file or stream without affecting the rest of the data.

       The  variable and function definitions in each -f source file are read and compiled.  The -e expr option can be used to define variables on
       the command line.  Since many of the characters in an expression have special meaning to the shell, it should usually be enclosed in single
       quotes.	 The -s svar=sval option can be used to assign a string variable a string value.  If this string variable appears in an input for-
       mat, only records with the specified value will be processed.

       The -b option instructs the program to accept only exact matches.  By default, tabs and spaces are ignored except as field separators.  The
       -l option instructs the program to ignore newlines in the input, basically treating them the same as tabs and spaces.  Normally, the begin-
       ning of the input format matches the beginning of a line, and the end of the format matches the end of a line.  With  the  -l  option,  the
       input format can match anywhere on a line.

       The  -w option causes non-fatal error messages (such as division by zero) to be supressed.  The -u option causes output to be flushed after
       each record.  The -n option tells the program not to get any input, but to produce a single output record.   Otherwise,	if  no	files  are
       given, the standard input is read.

       Format  files  associate  names with string and numeric fields separated by literal information in a record.  A numeric field is given in a
       format file as a dollar sign, followed by curly braces enclosing a variable name:

	    This is a numeric field: ${vname}

       A string variable is enclosed in parentheses:

	    This is a string field: $(sname)

       The program attempts to match literal information in the input format to its input and assign string and numeric fields accordingly.  If  a
       string or numeric field variable appears more than once in the input format, input values for the corresponding fields must match (ie. have
       the same value) for the whole record to match.  Numeric values are allowed some deviation, on the order of 0.1%, but string variables  must
       match exactly.  Thus, dummy variables for "don't care" fields should be given unique names so that they are not all required to take on the
       same value.

       For each valid input record, an output record is produced in its corresponding format.  Output field widths are	given  implicitly  by  the
       space  occupied	in the format file, including the dollar sign and braces.  This makes it impossible to produce fields with fewer than four
       characters.  If the -b option is specified, input records must exactly match the template.  By default, the character following each  input
       field  is  used	as a delimiter.  This implies that string fields that are followed by white space cannot contain strings with white space.
       Also, numeric fields followed but not preceded by white space will not accept numbers preceded by white space.  Adjacent input  fields  are
       advisable only with the -b option.  Numeric output fields may contain expressions as well as variables.	A dollar sign may appear in a lit-
       eral as two dollar signs ($$).

       The definitions specified in -e and -f options relate numeric output fields to numeric input fields.  For  the  default	record	format,  a
       field is a variable of the form $N, where N is the column number, beginning with 1.  Output columns appear on the left-hand side of assign-
       ments, input columns appear on the right-hand side.

       A variable definition has the form:

	    var = expression ;

       Any instance of the variable in an expression will be replaced with its definition.

       An expression contains real numbers, variable names, function calls, and the following operators:

	    +  -  *  /	^

       Operators are evaluated left to right.  Powers have the highest precedence; multiplication and division are evaluated before  addition  and
       subtraction.  Expressions can be grouped with parentheses.  All values are double precision real.

       A function definition has the form:

	    func(a1, a2, ..) = expression ;

       The  expression	can contain instances of the function arguments as well as other variables and functions.  Function names can be passed as
       arguments.  Recursive functions can be defined using calls to the defined function or other functions calling the defined function.

       The variable cond, if defined, will determine whether the current input record produces an output record.  If cond is positive,	output	is
       produced.  If cond is less than or equal to zero, the record is skipped and no other expressions are evaluated.	This provides a convenient
       method for avoiding inappropriate calculations.	The following library of pre-defined functions and variables is provided:

       in(n)	 Return the value for input column n, or the number of columns available in this record if n is 0.  This is an	alternate  way	to
		 get a column value instead of using the $N notation, and is more flexible since it is programmable.  This function is disabled if
		 an input format is used.

       if(cond, then, else)
		 if cond is greater than zero, then is evaluated, otherwise else is evaluated.	This function is necessary for	recursive  defini-
		 tions.

       select(N, a1, a2, ..)
		 return  aN (N is rounded to the nearest integer).  This function provides array capabilities.	If N is zero, the number of avail-
		 able arguments is returned.

       rand(x)	 compute a random number between 0 and 1 based on x.

       floor(x)  return largest integer not greater than x.

       ceil(x)	 return smallest integer not less than x.

       sqrt(x)	 return square root of x.

       exp(x)	 compute e to the power of x (e approx = 2.718281828).

       log(x)	 compute the logarithm of x to the base e.

       log10(x)  compute the logarithm of x to the base 10.

       PI	 the ratio of a circle's circumference to its diameter.

       recno	 the number of records recognized thus far.

       outno	 the number or records output thus far (including this one).

       sin(x), cos(x), tan(x)
		 trigonometric functions.

       asin(x), acos(x), atan(x)
		 inverse trigonometric functions.

       atan2(y, x)
		 inverse tangent of y/x (range -pi to pi).

EXAMPLE

       To print the square root of column two in column one, and column one times column three in column two:

	 rcalc -e '$1=sqrt($2);$2=$1*$3' inputfile > outputfile

AUTHOR

       Greg Ward

BUGS

       String variables can only be used in input and output formats and -s options, not in definitions.

       Tabs count as single spaces inside fields.

SEE ALSO

       cnt(1), ev(1), getinfo(1), icalc(1), rlam(1), tabfunc(1), total(1)

RADIANCE
							      4/6/99								  RCALC(1)