As I mentioned in my comments above, a call warrant is a long term option (the right to buy the stock at the strike price but with a further expiration). In common usage, warrants are assumed to be call warrants unless specified as put warrants (the right to sell the stock at the strike price).
PTE's secondary offering consists of a unit which is comprised of one share and one seven year warrant with a strike price of $2.80. Each unit costs $2.35. The warrants are American style, giving the owner the right to exercise them at any time. If PTE rises sharply, warrant holders will be able to buy shares at $2.80 (one share per warrant unless specified differently in the prospectus). With 10.6 million units offered, that will raise $25 million for the company (before underwriter fees), excluding future proceeds from exercise of warrants. The units will be separable immediately and will trade on its own.
Because each unit costs $2.35, that means that they priced the share below $2.35 ($2.35 less the value of the warrant). I can't tell you what a 7 year warrant with a strike price of $2.80 should be worth but you'll know that as soon as it begins trading. My guess is that the pricing of the common share will effectively be less than $2. Whatever that number is, that's a sharp discount to $3.18 which is where PTE closed at yesterday. That's what I meant by "they threw investors under the bus". It's no wonder that the shares dropped like a rock today.