undefined variable generated for precompute

[RandomY-2]

hi,

i was playing around with the precompute scheduling command, but for this example

http://tensor-compiler.org/codegen.html?expr=q(i,%20j)%20=%20A(i,%20j)%20*%20B(i)&format=q:ss:0,1;A:ss:0,1;B:s:0&sched=precompute:A(i,%20j)%20*%20B(i):i:i

the comput function uses an iworkspace variable which is not defined anywhere. Is there a precondition for when precompute can be used? thanks