concave function

(redirected from Concave downward)

concave function

[′kän‚kāv ′fəŋk·shən]
(mathematics)
A function f (x) is said to be concave over the interval a,b if for any three points x1, x2, x3 such that a <>x1<>x2<>x3<>b, f (x2)≥ L (x2), where L (x) is the equation of the straight line passing through the points [x1, f (x1)] and [x3, f (x3)].
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Because the unloading curves predicted by Schapery's model were in a concave downward configuration, the ratcheting strains were invariably underestimated in every loading cycle.
However, they show different curvatures: the loading curve is concave downward as it lies below its tangent lines at any point, while the unloading curve is concave upward as it lies above all its tangents.
The experiment found that, though the group exposed to varying quantities of light did have relative spikes in pressure output, it graphically spiked initially and rotated between concave upward and concave downward with respective exposure to light and to no light.