Introduction | Time Tool | Vector Geometry Tool | Calculation Tool | Spatial Analysis Tool
STK Analysis Workbench Tools
Calculation Tool
The Calculation Tool includes components of the following basic types: Scalar, Condition, and Parameter Set.
| Calculation Tool Components | ||
|---|---|---|
| Icon | Name | Description |
|
Scalar | Defines components that produce scalar time-varying calculations. Scalar calculation components also have the ability to return minimum, maximum, mean, and standard deviation values. |
|
Condition | Defines a scalar calculation which is considered to be satisfied when it is positive and not satisfied when it is negative. |
|
Parameter Set | Defines a set of related scalar calculations. |
All of these types define components that produce time-varying computational results that can be reported, graphed, transformed, and analyzed further.
You can generate reports and graphs of these components directly from the Calculation Tool without the need to define specific styles in the Report & Graph Manager. The appropriate styles are created automatically based on the selected component.
You can store the resulting report or graph (including as a Quick report), which will make it available in the Report & Graph Manager.
Alternatively, every calculation component is also available as a data provider and you can access them directly via the Report & Graph Manager.
The basic types included in the Calculation Tool correspond to three main uses of calculations in STK: general reporting and graphing, trending scalar calculations for finding minimums and maximums, and configuring conditions based on scalar calculations that determine if they fall within specified bounds.
Scalar calculations in particular enable you to create new calculations using various functional operations as well as calculus, such as differentiation and integration.
Calculation Component types
The Calculation Component Add/Edit windows enable you to specify various properties of a component that you have added or selected for modification.
Shared Properties | Scalar Calculations | Parameter Sets | Conditions | Condition Sets
Shared Component properties
Components for STK's Analysis Workbench capability share a number of properties as listed below that you can access when adding or modifying components.
| Component Properties | |
|---|---|
| Option | Description |
| Type | Click to reveal the list of available component types. |
| Name | Displays the name of the selected component or allows the naming of a newly created component. When naming new components, spaces will be replaced with an underscore and invalid characters will be replaced with a hyphen. |
| Parent | Displays the component's parent object. Click to change or select the component's parent object. |
| Description | You may add descriptive text to this field. |
| Type Description | This is a read-only field that contains a short description of the component type. |
Defining Scalar calculations
Scalars define components that produce scalar time-varying calculations. For example, the following Scalar component is available for Satellite objects:
ElapsedTimeFromStart
In addition, any component of Scalar type may also define subcomponents that represent its maximum and minimum as other Scalar components, as well as Time Instant and Time Array components in the Time Tool. The former represents the times of its global maximum/minimum and the latter represents times of its local maximums/minimums.
The following types of Scalar components are available:
| Type | Description |
|---|---|
| Angle | This is an angular displacement specified by an Angle component from the Vector Geometry Tool. |
| Average |
This is the average value computed by dividing the value numerically integrated over specified intervals of time by the duration of those intervals. Advanced Options... include settings for sampling and convergence, type of integration, and interpolation as well as the overall interval of integration specified by an Interval List component from the Time Tool. |
| Calculation Along Trajectory | This is a scalar calculation defined by evaluating the spatial calculation along the trajectory of the specified point. |
| Constant | This is an explicitly specified constant of a certain dimension and unit, e.g., 5 km, if you set dimension to Distance. |
| Custom Inline Script |
This is a Scalar Calculation using a scripted inline function in MATLAB, VBScript, or JScript that defines values and rates. Inline functions are used for simple calculations. Click to supply a value function and derivative function to be evaluated, the arguments to be used by the functions, and the unit dimension of the calculated value. When computed, STK creates a function with the inputs listed under Arguments, returning the values computed by the value function and derivative function. For more information, see Setting Arguments and Expressions. |
| Custom Script | A custom scalar calculation implemented using a script written in MATLAB, Perl or VBScript scripting language. For more information see Use Plugin Scripts and Vector Geometry Tool Plugin Points. |
| Data Element | Lists every scalar time-varying element from the STK data provider system which allows you to take advantage of existing STK computational output and incorporate it into the new framework within the Calculation Tool. Advanced Options... include settings for saving, sampling, and interpolation. |
| Derivative | This is the derivative of another Scalar component. The value of Derivative is normally computed using analytic formulas; however, you can force the use of numerical differences using the check box. STK always uses numerical differences to compute the derivative of this Derivative component. STK uses the Differencing Time Step value when computing the numerical differences. When possible, it uses a second order differencing formula, e.g., for central differencing. |
| Dot Product | This is the dot product between two specified vectors of the Vector Geometry Tool.
There is an option to first normalize the vector before computing the dot product. |
| Elapsed Time | This is the time elapsed since a specified reference Time Instant component from the Time Tool. Elapsed time can be positive or negative. |
| File | Produces scalar calculations by interpolating tabulated data contained in an external ASCII file (*.csc) that contains columns of times, scalar values, and optional scalar rate values. Click the Filename field ellipsis (...) button and enter the desired path and filename. |
| Fixed at Time Instant | This is a constant obtained from another Scalar component by evaluating it at a fixed time specified by a Time Instant component from the Time Tool. |
| Function (x) | This is a function of either another Scalar component or a time elapsed from a specified Time Instant component from the Time Tool. Available functions include power, trigonometric, logarithmic, and exponential. The resulting calculation can either inherit its dimension from its argument or can have a dimension assigned explicitly. |
| Function (x,y) | This is a function defined by performing a specified operation on two Scalar components, x and y. The resulting calculation can inherit its dimension from argument x or argument y, or can have a dimension assigned explicitly. |
| Integral | This is a numerical quadrature of another Scalar component that can be computed as:
|
| Plugin | This is a scalar calculation defined by using a COM component you define.
The Plugin type is not valid as a template. |
| Standard Deviation |
STK computes the standard deviation value as the square root of the average squared difference between actual values and the average value over specified intervals of time. Advanced Options... include settings for sampling and convergence, type of integration, and interpolation as well as the overall interval of integration specified by an Interval List component from the Time Tool. |
| Surface Distance Between Points | This is the surface distance of the minimum geodesic along the selected central body ellipsoid between the surface projections of the selected points. |
| Vector Magnitude | This is the magnitude of the Vector component from the Vector Geometry Tool. |
Defining Calculation Parameter Sets
Parameter Sets define a set of related scalar calculations. You can organize them into multiple nested parameter sets, but each parameter set contains related calculations that typically represent various aspects or parameterizations of one common phenomenon.
The following types of Parameter Set components are available:
| Type | Description |
|---|---|
| Attitude | Defines the orientation of one set of Axes from the Vector Geometry Tool relative to another. This parameter includes the following subsets: Quaternion, Euler, DCM, and AngleAxis. Quaternion includes four quaternion elements: Q1, Q2, Q3, and Q4. Euler includes all 12 sequences where within each there are three angles A, B, and C. DCM includes all nine elements of the direction cosine matrix, e.g., XX, XY, etc. AngleAxis includes X, Y, and Z components of the unit axis of rotation and RotationAngle. |
| Cartographic Trajectory | Defines the position of a specified Point from the Vector Geometry Tool with respect to a specified Central Body. This parameter set includes the following subsets: Cartesian, Centric, and Detic. Cartesian includes X, Y, Z, and Radius. Centric includes LLR (Latitude, Longitude and Radius) and SubPoint (X, Y, Z, and Radius). Detic includes LLA (Latitude, Longitude and Altitude), SubPoint (X, Y, Z, and Radius), and SurfaceNormal (X, Y, and Z). |
| Orbit | Defines orbital element sets for a Point from the Vector Geometry Tool orbiting a specified Central Body in a specified coordinate System. Element sets include Cartesian, Classical, Delaunay, Spherical, and Equinoctial (Posigrade and Retrograde). |
| Trajectory | Defines the position of a specified Point from the Vector Geometry Tool with respect to a reference System. This parameter set includes the following sub-sets: Cartesian, Cylindrical, and Spherical. Cartesian includes X, Y, Z, and Radius. Cylindrical includes Azimuth, Height, and Radius. Spherical includes Azimuth, Elevation, CoElevation, and Radius. |
| Vector | Defines the representation of a specified Vector from the Vector Geometry Tool with respect to a specified set of Axes. This parameter set includes the same types of subsets as Trajectory type. |
Defining Calculation Conditions
Conditions define a scalar calculation that is considered to be satisfied when it is positive and not satisfied when it is negative.
The following types of Condition components are available:
| Type | Description |
|---|---|
| Combined | Combines multiple constituent conditions using one of several merging operations:
The Minus operation is available when there are only two components in the combined list. |
| Scalar Bounds | Defines a condition by combining a specified Scalar component with scalar bounds. The resulting condition can be defined as satisfied using one of the following options:
|
| Trajectory Within Volume | This is a condition determined by whether the trajectory of the specified point appears inside a volume defined implicitly by the selected spatial condition. |
Defining Calculation Condition Sets
The following types of Condition Set components are available:
| Type | Description |
|---|---|
| Scalar Thresholds |
This is a condition set based on comparing a scalar to a set of thresholds. Click Thresholds... to add threshold values. |