DiffTime[expr]

DiffTime[v,a]

expr: algebraic expression, equality involving algebraic expressions, or a set, list, table, or array of algebraic expressions

v: Mambo vector

a: name of defined triad

The function DiffTime returns the derivative with respect to time of expr. If expr depends explicitly on time, a variable name associated with time must be declared using the SetTime function.

In the second form, the function DiffTime returns the derivative of the vector v relative to the triad a.

Note that a time derivative of a variable is denoted by a superscribed prime to the right of the variable name.

Restart;
DeclareTriads[a,b];
DefineTriads[a,b,theta,3];
DeclareStates[theta];
w:=MakeTranslations[{a,1},{b,2}];
DiffTime[w,a]

$\left\{''Type''\to ''Vector'',''Size''\to 1,1\to \left\{''Coordinates''\to \left\{-{\mathrm{theta}}^{\prime },0,0\right\},''Triad''\to b\right\}\right\}$

DiffTime[{theta,3*theta^2}]

$\left\{{\mathrm{theta}}^{\prime },6\mathrm{theta}{\mathrm{theta}}^{\prime }\right\}$

DeclareStates, LinearVelocity, AngularVelocity, SetTime