You are not calling the QUAD routine correctly. See the documentation for examples. The second argument is the name of the function ("FUN") and the third is a two-element vector that gives the endpoints of the domain of integration:
call quad(z,"FUN", yLow || yHigh); /* integral on interval [yLow, yHigh] */ print z;
call quad(z,"FUN", {1 13}); /* integral on interval [1, 13] */ print z;
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