lowest(node-set-1 [, stored-expression])
This function returns (as a node-set) the node from node-set-1 that has the lowest value of the supplied stored expression, evaluated as a number. If the stored expression is omitted, the expression "number(.)" is evaluated: that is, the string value of the node, converted to a number. A stored expression may be obtained as the result of calling the saxon:expression function.
The stored expression is evaluated for each node in node-set-1 in turn, with that node as the context node, with the context position equal to the position of that node in node-set-1, and with the context size equal to the size of node-set-1. Any NaN values are ignored. If the node-set is empty, the result is an empty node-set. If several nodes have the lowest value, the result node-set contains the one that is first in document order. This differs from the EXSLT lowest() function, which returns all the nodes that have the minimum value.
Example: saxon:lowest(sale, saxon:expression('@price * @qty')) will evaluate price times quantity for each child <sale> element, and return the node for which this has the lowest value.