Cauchy–Riemann equations, an Uncommon card

The card carries these facts from its Wikipedia article.

• The equations are and where u and v are real bivariate differentiable functions.
• Typically, u and v are the real and imaginary parts, respectively, of a complex-valued function f = f = u + i v of a complex variable z = x + iy.
• If f is complex-differentiable at a complex point z = x + iy, then the partial derivatives of u and v exist and satisfy the Cauchy–Riemann equations at that point.

Rarity in WikiCards follows a year of Wikipedia page views: the most read articles become Epic and Legendary cards. The Cauchy–Riemann equations article was read about 58,000 times in a year. ATK comes from the length of the article and DEF from its quality, so this card hits with 71 and blocks with 50: each hit it takes is cut by 20 %.

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The cards just above and just below Cauchy–Riemann equations in the power ranking, all domains together.