# Evaluate Formula (Multi-Variable) (G Dataflow)

Calculates one or more function values of a given formula that contains multiple variables.  ## formula

Formula of n independent variables. The formula can contain any number of valid variables.

Entering Valid Variables

This node accepts variables that use the following format rule: variables must start with a letter or an underscore followed by any number of alphanumeric characters or underscores. ## x values

Values of the variables where this node calculates function values.

This input accepts the following data types:

• 1D array of double-precision, floating-point numbers
• 2D array of double-precision, floating-point numbers

For 1D array inputs, each array element represents the value of the corresponding variable in variables.

For 2D array inputs, the ith row of the array contains the fixed values of the ith variable of the n-dimensional function. The other dimension of the array marks the n-dimension points at which this node calculates function values. ## variables

n independent variables of the given formula. variables has a one-to-one relation with x values. ## error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error  If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error ## y value

Function value(s) at x values

This output can return the following data types:

• Double-precision, floating-point number
• 1D array of double-precision, floating-point numbers

Algorithm for Calculating y value

If x values is a 1D array of double-precision, floating-point numbers, this node calculates y value using the following equation: y = f(x1, x2, ..., xn), where n is the number of independent variables in the given formula.

If x values is a 2D array of double-precision, floating-point numbers, this node calculates y values using the following equation:

yi = f(x1i, x2i, …, xni)

where

• n is the number of dimensions of the given set of points
• f is an n-dimensional function given by the formula
• x1, x2, …, xn are n independent variables ## error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error  If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

The following table shows examples of the inputs and outputs of this node.

formula x values variables y values
3*x1 + 4*x2 + x3^2 [1, -1, 2] [x1, x2, x3] 3
[1, 0; -1, 4; 2, 1] [3,17] Note

In x values, [1, -1, 2] are the values for [x1, x2, x3] in the first iteration; [0, 4, 1] for the second.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application