I've just installed htop on a Dell Latitude E6530. I'm puzzled by a number of questions relating to the processor status bars. Unfortunately the man page doesn't really address my questions.

As far as I knew I had 4 cores, but there are 8 processor bars The help menu says that the left bars are for CPU 1/2, the right bars for CPU 2/2. Does this mean that there are 4 cores per CPU?

My other question is, how can I associate jobs with processor bars? Currently I'm running one big matlab job, using 100% of 1 core. But the core keeps jumping around, 1 of the processor bars is always showing 100% but every few seconds the full processer switches among the 8, i.e., any one of the bars could be the full one at any minute. Is this to be expected?

Thanks very much for any advice.

Probably your CPU is quad core Core i5/i7 with Hyper-Threading Technology. HTT allows to execute two threads of commands for every core simultaniously, so for OS it is like 8 cores.
And CPU switches periodically current task to another core, so you can see it in htop output.

Take a look at cat /proc/cpuinfo output