IS NUMBER

IS NUMBER

Let Subcommand

Determine whether a previously defined string defines a valid numerical value.

There are times where it may be useful to determine if a previously defined string defines a valid numeric value or not. The primary motivation for this command is to distinguish if a string is a parameter name or a number (e.g., when using command line arguments).

Dataplot determines this by attempting an internal Fortran read. That is (where STR is the string being tested),

READ(STR,*,IOSTAT=IE)AVAL

If IOSTAT does not indicate an error, then STR is assumed to be a number. If IOSTAT does indicate an error, then STR is assumed to not be a number.

Note that there are some strings that are ambiguous in that they can be interpreted as either a valid number or a parameter name. For example, 1D0 will be read successfully as a number, but it is also a valid parameter name in Dataplot. Determining whether this should be considered a number or a parameter will be dependent on the specific application. The basic rule for this command is that if it can be successfully read as a number it will be considered a number.

LET <ival> = IS NUMBER <sorg>
where <sorg> is a previously defined string;
and <ival> is a parameter.

The <ival> will be set to 1 if <sorg> is determined to be a number and set to 0 if <sorg> is determined to not be a number.

LET STRING S1 = PARNAME
LET IFLAG = IS NUMBER S1
LET STRING S2 = 34.56
LET IFLAG = IS NUMBER S2

The string on the right hand side of the equal sign must be a previously defined string. String expressions are not allowed. So
LET IFLAG = IS NUMBER "45.6"

should be coded as

LET STRING S1 = 45.6
LET IFLAG = IS NUMBER S1

None

None

CHARACTER (LET)	= Convert numeric values to strings based on the ASCII collating sequence.
UPPER CASE	= Convert a string to upper case.
LOWER CASE	= Convert a string to lower case.
LET FUNCTION	= Defines a function.
LET STRING	= Defines a string.
READ STRING	= Reads a string from a file.
SUBSTITUTE CHARACTER (^)	= Substitute the value of a string or parameter.
CONCATENATE CHARACTER (&)	= Concatenate two strings.
SUBTRING	= Extract a substring from an existing string.
STRING INDEX	= Extract the start/stop positions of a substring within a string.
STRING CONCATENATE	= Concatenate one or more previously defined strings.
STRING EDIT	= Edit a string.
STRING MERGE	= Insert a string into another string without overwrite.
STRING REPLACE	= Insert a string into another string with overwrite.
STRING LENGTH	= Return the length of a string.
GROUP LABEL	= Define the text for group labels.

Data Management

2020/11

 
CALL MACRO.DP  K=3.56
    

where MACRO.DP contains

 
LET STRING SORG = $k
LET IFLAG = IS NUMBER SORG
IF IFLAG = 1; . ARGUMENT IS A NUMBER
   LET AVAL = ^SORG
ELSE IF IFLAG = 0; . ARGUMENT IS A STRING
   IF SORG EXISTS
      LET AVAL = ^SORG
   ELSE
      LET AVAL = -9999
   END OF IF
END OF IF