how to get the max value in an array

hi guys:    I'm using int[] in postgrsql to store int array. I want to get max 
value of each row . While I can't find any function to get it(max 
function will get max array in one column) . Even I could write a sql 
function to get the max value. I still think a native funtion is better 
. Can your guys help me?    Thanks