Glistam referred to it, and "Man with no name" provided a link, in short, the California Appeals Court, in People v. Pellecer, ruled that carrying a fixed-blade inside a parcel (backpack, duffle bag, briefcase, etc) is not considered to be "concealed upon the person", and is therefore not illegal in the state of California. The statute in the California penal code that says carrying a concealed fixed-blade is illegal specifically says "concealed upon the person" (CA penal code 21310), and this is illegal all throughout the state.
Los Angeles has no statute, county or municipality, that makes carrying a fixed-blade in a parcel illegal. I know of no county or municipality within the state of California that does.
Zzyzzogeton is correct that openly carrying a fixed-blade in Los Angeles with a blade longer than 3 inches is illegal, both in LA county and city, but there are exceptions- if you are openly carrying a fixed-blade with a blade longer than 3" for "legitimate" work or recreational activities (camping, fishing, etc) or for religious reasons, and you can prove that your reason is legitimate, then openly carrying such a knife is legal.
And just to throw it in, having a fixed-blade in a vehicle, out of sight, is also NOT considered "concealed" under the law, and is therefore legal throughout the state.