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• Pno% is the number that refers to the TeLiTab sets in the Data slot. Pno% should be an integer value or a parameter which is assigned an integer value and is the number of the TeLiTab set in the expressions' data slot.
• Npoints% is the number of points (x,y) that are given in direct definition.
• @ObjFn() refers to the Object from which data will be used.
• TeLiTab$ TeLiTab$ refers to the string parameter that contains the TeLiTab.
• Ndim% is the number of dimensions (or columns in the table...).
• "ColLab$_1" and @ObjColPar_1 refer to the column that will be used as the parameter X in the interpolation.
• "ColLab$_2" and @ObjColPar_2 refer to the column that will be used as the parameter Y in the interpolation. etc.
• Xint is the parameter to do interpolation on.
• Xtrap% is an optional argument to switch off a warning in the event of extrapolation. If Xtrap% = 1 no warning is given. The value is not required and is 0 by default (not suppressing the warning).

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1. See also Telitab access for a generic description on the use of TeLiTab data
2. Similar to other Data analysis functions, the DQUAD function provides a convenient way to manipulate curve data, either available in the knowledge base or produced by satellites. The routine contains a double quadratic interpolator. Extrapolation outside the x-range is performed parabolic.
3. Please realise the dataset provided to DQUAD should be a function. Every x-value should have one y-value. When you do not have a valid dataset, please look at GAUSSINT() or LEASQ()

Examples

Syntax 1: TeLiTab in Dataslot

The function y is defined as

y = DQUAD(1, 2, "XC", "YC", x, 1)

With the following Telitab set in the Data slot:

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If Pno%=0 then all x_i and y_i values should be numeric expressions. The minimum number of x,y data points Npoints% in the list is 2 in which case the interpolation (and differentiation) is performed linear. Let y be a function defined by

y = DIFF(0, 4, 1, 1, 2, 4, 3, 9, 4, 16, x, 1)

For x=2.5, this equation returns

y=6.25

Syntax 3 and 4: TeLiTab in object or string

These methods are similar to syntax 1, for information on how to acces the TeLiTab data with those methods see: TeLiTab access. 

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