This isn't really my own answer. I just want to squeeze what naturallyinconsistent said into a nut shell.

In that nutshell: The "waveform" of white light is uninteresting. It's uninteresting because white light is the superposition of many different "waveforms." Usually, it's so many that describing it's shape would be a futile exercise. But, because superposition is a linear phenomenon, it's also completely unnecessary to describe it. Everything we want to know about white-light-as-waves can be understood as the sum of what we know about its individual component waves.