It's not yet 8 a.m. I'm in the bathroom washing my face, Math Man is getting ready to get in the shower. He turns to me and says, "So if you take the partial derivative of r with respect to x...well, actually the second partial derivative..."
"Where r is the square root of x squared plus y squared plus z squared?" wondering if he is really talking to me, or just thinking aloud.
"No, no, just x and y," he clarifies.
Unbidden the chain rule flowers in my brain, 2x times a half...divided by the square root, right and then we'll need the product rule. We don't keep a white board marker in the bathroom, despite its inviting plethora of glass surfaces. I'm not sure why, there's one in the kitchen and in the downstairs bathroom, where math gets inscribed on the panes of glass in the door and on the mirror. We have a glass sheet screwed to the wall in the downstairs hallway for the purpose. But I digress...
"Does it surprise you that it blows up?" wonders Math Man.
"Oh, no...that derivative shows up in some operators."
Sweet talk between lovers in the morning.
Love your understated humor!
ReplyDeleteThe whole conversation made me laugh this morning.
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