DensityHistogram[{{x_1, y_1}, {x_2, y_2}, ...}] plots a density histogram of the values {x_i, y_i}.DensityHistogram[{{x_1, y_1}, {x_2, y_2}, ...}, bspec] plots a density ...

DensityPlot[f, {x, x_min, x_max}, {y, y_min, y_max}] makes a density plot of f as a function of x and y.

DependentVariables is an option which specifies the list of all objects that should be considered as dependent variables in equations that have been supplied.

Deployed is an option for displayed objects, cells, and notebooks that specifies whether their contents should be considered deployed, so that elements such as Slider, ...

Deploy[expr] yields a deployed version of expr in which elements such as Slider, InputField, Locator, and Button are active, but general editing and selection is disabled.

DepthFirstScan[g, s, {"event_1" -> f_1, "event_2" -> f_2, ...}] performs a depth-first scan of the graph g starting at the vertex s and evaluates f_i whenever "event_i" ...

Depth[expr] gives the maximum number of indices needed to specify any part of expr, plus 1.

DerivativeFilter[image, {n_1, n_2}] computes the n_i\[Null]^th derivative of image in the vertical and horizontal directions.DerivativeFilter[image, {n_1, n_2}, \[Sigma]] ...

f' represents the derivative of a function f of one argument. Derivative[n_1, n_2, ...][f] is the general form, representing a function obtained from f by differentiating n_1 ...

DesignMatrix[{{x_11, x_12, ..., y_1}, {x_21, x_22, ..., y_2}, ...}, {f_1, f_2, ...}, {x_1, x_2, ...}] constructs the design matrix for the linear model \[Beta]_0 + \[Beta]_1 ...