About triu error in time code

General Usage
1

UndefVarError: triu not defined

Stacktrace:
[1] GMRES_NoRestart(n::Int64)
@ Main .\In[2]:5
[2] macro expansion
@ .\In[3]:2 [inlined]
[3] top-level scope
@ .\timing.jl:262 [inlined]
[4] top-level scope
@ .\In[3]:0