Translations:Expression Manager/31/en

Here weight_kg is {if(weight_units == 'kg', weight, weight * .453592)}.  This if() function means that if the subject entered the weight using kilograms, use that value, otherwise multiply the entered value (which was in pounds) by .453592 to convert it to kilograms.  The height_m variable uses a similar approach to compute the person's height in meters, even if he entered his height in inches.