Format

DIF1(id)

Description

Returns the time derivative of the state variable defined by the Control_Diff element. For implicit Control_Diff elements, the time derivative is approximate, obtained using numerical differentiation.

Example

<Force_Vector_TwoBody

    id                   = "30101"

    type                 = "ForceOnly"

    i_marker_id          = "30102040"

    body1_id             = "30102"

    j_floating_marker_id = "30101041"

    body2_id             = "30101"

    ref_marker_id        = "30101010"

    ref_body_id          = "30101"

    fx_expression        = "0"

    fy_expression        = "0"

    fz_expression        = "0.01*DIF(301001)+
                            0.0001*DIF1(301001)"

 />

<Control_Diff

    label                = "Diff/301001"

    id                   = "301001"

    is_implicit          = "FALSE"

    ic                   = "0."

    ic_dot               = "0."

    is_static_hold       = "FALSE"

    type                 = "EXPRESSION"

    expr                 = "DZ(30102020,30101010)"

 />

Arguments

id

The ID of the Control_Diff element.