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Number::Spice - handling of Spice number strings


    use Number::Spice qw(:convert);

    print spice_to_number('5u');      # 5E-6
    print spice_to_number('1.0e4k');  # 1.0E7

    print number_to_spice(1.0e12); # 1T
    print number_to_spice(1.0e-2); # 10M (i.e. milli, not mega!)


Number::Spice was written to support the number format used in the syntax for netlists for the spice electrical circuit simulator. This number format is also used in other applications, even in different fields. Number::Spice can be used to any purpose, and does not require the installation of the spice simulator.

Spice syntax provides a shortcut for writing down numbers in scientific notation, by appending a suffix to the value which corresponds to a numeric multiplier. The following table lists the minimal suffices and the corresponding multiplier:

        T       1.0E12
        G       1.0E9
        MEG     1.0E6
        X       1.0E6
        K       1.0E3
        M       1.0E-3
        MIL     2.54E-5 (i.e. 1/1000 inch)
        U       1.0E-6
        N       1.0E-9
        P       1.0E-12 
        F       1.0E-15
        A       1.0E-18



The following functions are provided. All functions are available for exporting.


Returns the regular expression matching a Spice number.


Returns true is the given string matches a Spice number after removal of leading and trailing whitespace. Note that a plain number, i.e. without literal suffix, is also accepted as a valid Spice number.


Examines a string and returns a list holding a number and a spice suffix if the string holds a valid spice number. Returns undef otherwise.

Note that a regular number is also considered to be a spice number, and an empty string will be returned as the suffix in this case.


Returns the value of a given spice suffix, e.g. suffix_value('giga') yields 1.0E9.


Returns a regular number represented by the given spice number. spice_to_number() will die() if the given number is not a spice number.


Returns the shortest spice number representing the given number. Note that no conversion to mil will be attempted, and numbers smaller than 1.0E-18 will not get a suffix.


Converts a spice number to its shortest form by invoking spice_to_number() and number_to_spice().


In addition to the methods, the following scalars representing regular expressions are also made available for exporting:


matches a regular number


matches any spice suffix


matches a spice number. Note that a regular number is considered a spice number with no suffix. If you need to check for pure spice numbers, i.e. numbers with a literal suffix, check with /$RE_NUMBER$RE_SPICE_SUFFIX\b/ instead.


The functions and regular expressions are tagged into the following groups for easy importing:


spice_to_number(), number_to_spice() and normalize_spice_number()




All conversion functions and regular expressions


More info on the Spice format is given in the on-line Spice3 manual at the University of Exeter, located at

And to those who were looking for numbers on the Spice Girls, but unfortunately stranded here, take a peek at their official home page: ;-)


Wim Verhaegen <>


Copyright (c) 2000 Wim Verhaegen. All rights reserved. This program is free software; you can redistribute and/or modify it under the same terms as Perl itself.