In addition to integer data values, floating point types may be used, but "simple decimal fractions like 0.1 or 0.7 cannot be converted into their internal binary counterparts without a little loss of precision," sometimes giving surprising results. Also, do not compare two "float" type numbers for equality.
Example 591. Creation using integer and floating values
$measurement = 1234.7;
$unit = new Zend_Measure_Length((integer)$measurement,
// outputs '1234 m' (meters)
$unit = new Zend_Measure_Length($measurement, Zend_Measure_Length::STANDARD);
// outputs '1234.7 m' (meters)