Ravel’s mathematical operators

Ravel has a large number of mathematical operators which are accessed via the widget bar. The top-level menu items are shown in Figure 40.

The menus are respectively:

Binary operators that take 2 (or more) inputs;
Fundamental constants: e, π , 0, 1, ∝ , and the percentage operator %;
Unary operators with only one input;
Running sum and product and difference operators;
Statistical functions (mean, median, standard deviation, etc.); and
Mathematical operators for handling multi-dimensional data: dot, inner and outer products, etc.

Figure 40: The mathematical operators menu bar

Click on one of these menu widgets, and the relevant selection of operators will be displayed above the bar. Click on one of these operators, and it will be attached to the mouse cursor for you to place on the canvas. The full complement of operators, aligned with the menu which invokes them, is shown in Figure 41.

Figure 41: Ravel's full complement of mathematical functions

Full details on each of these operators are given via in-context help: hover over an operator, bring up the right-click/context menu, and choose Help.

Operators can be entered onto the canvas by either clicking on the relevant menu and then operator, or by typing its text shortcut on the canvas.

Table 1: The binary menu

Operator	Operation	Shortcut
	Add two or more variables together	+
	Subtract two or more variables. Inputs to the upper (+) and lower (-) inputs are frst added together, then the sum of the input to (-) are subtracted from the sum of the inputs to(+)	<Enter>
	Multiply two or more variables together.	*
	Divide one or more variables by others. Inputs to the upper (x) and lower (÷) inputs are frst multiplied together, then the product of the input to(x)are divided bytheproduct of the inputs to(÷)	/
	Return the minimum of two inputs	min
	Return the maximum of two inputs	max
	Return 1 if two inputs are both true (equal to or greater than 1), else return 0	and
	Return 1 if one input is true (equal to or greater than 1), else return 0	or
	Return the log of the inputs to base a.	log
	Return x to the power of y	pow
	Polygamma function. For mathematicians. This is a component of the_Minsky_simulation engine.	polyGamma
	Return 1 if x<y else return 0	le

Return 1 if x≤y else return 0	leq
Return 1 if x=y else return 0	eq
Return the user-defned function with inputs x and y

Table 2: The fundamental constants menu

Operator	Operation	Shortcut
	Parameter equal to Euler’s e≅2.718281828459…	euler
	Parameter equal toπ ≅3.1415926535897932…	pi
	Parameter equal to 0	zero
	Parameter equal to 1	one
	Parameter for Infnity—generates 1.79769 multiplied by 10[308]	inf
	Takes an input variable and multiplies each element in it by 100	%

Table 3: The unary menu

Operator	Operation	Shortcut
	Return the square root of the inputted variable	sqrt
	Return Euler’s e raised to the power of the inputted variable x	exp
	Return the natural logarithm of the inputted variable	ln
	Return the sine of the inputted variable	sin
	Return the cosine of the inputted variable	cos
	Return the tan of the inputted variable	tan
	Return the inverse sine of the inputted variable	asin
	Return the inverse cosine of the inputted variable	acos
	Return the inverse tan of the inputted variable	atan
	Return the hyperbolic sine of the inputted variable	ainh
	Return the hyperbolic cosine of the inputted variable	cosh
	Return the hyperbolic tan of the inputted variable	tanh
	Return the magnitude of the inputted variable	abs

Return the integers of the inputted variable	foor
Return the inputted variable minus the integer parts
The Not operator. Return 0 if the input is <0.5 otherwise return 1	not_
Return the Gamma function of the input (for mathematicians)
Return the factorial of the input	fact

Table 4: The reduction menu

Operator	Operation	Shortcut
	Sum the inputs	sum
	Multiply the inputs	product
	Infmum: return the smallest value along an axis	infmum
	Supremum: return the biggest value along an axis	supremum
	Return 1 if any value along an axis is non-zero, otherwise return 0	any
	Return 1 if all values along a given axis are nonzero, otherwise return 0 if anyare zero.	all
	Infndex. Return the index (the position in an array) of the smallest value alongan axis
	Supindex. Return the index (the position in an array) of the greatest value alongagiven axis.

Table 5: The scan menu

Operator	Operation	Shortcut
	Running sum. Return the running sum of the input along a given axis
	The running product of the input tensor along a given axis
	Prior diference. Calculate the change in values along an axis looking backnsteps (the number of stepsnprior is entered in the edit form). The frstnentries on the axis are truncated.	diference
	Post diference. Calculate the change in values along an axis looking forwardnsteps (the number of stepsnprior is entered in the edit form). The lastnentries on the axis are truncated.	diferencePlus

Table 6: The statistics menu

Operator	Operation	Shortcut
	Return the mean (average) of the input	mean

	Returns the median along a named dimension	median
	Returns the standard deviation along a named dimension
	Returns the $k$-th moment about the mean along a named dimension.	moment
	Computes the histogram along a named dimension. The number of bins is set on the Edit menu	historgram
	Computes the covariance of two tensors along a named dimension. This returns a single number when two one-dimensional variables are compared, otherwise it returns a matrix of the covariance patterns across the additional dimensions	covariance
	Returns the correlation coeficient of the inputs. This returns a single number when two one-dimensional variables are compared, otherwise it returns a matrix of the correlations patterns across the additional dimensions.	correlation
Table 7: The te	Linear regression. This takes two arguments—the dependent (top input) and independent variable (bottom input)—and returns a linear regressionprediction for the dependent variable. nsor menu
Operator	Operation	Shortcut
	Inner Product. Generates a single number by multiplying all the elements of one vector(or tensor)byanother.
	Outer Product. Generates a matrix by the product of one vector with another
	Index. Returns the values in an array which are true for a logical condition.	index
	Gather. Returns values from the top input (x, the variable from which values will begathered), given the values in the bottom(i,the index)	gather
	Meld. Takes two or more variables with a shared dimension and combines their data on that dimension.	meld
	Merge. Takes two or more variables with shared dimensions and combines them on a new dimension specifed in the Edit feld.	merge
	Slice. Extracts a specifed number of data points from an input variable (the topten,etc.)	slice
	Size. Returns the number of elements along a named dimension	size
	Shape. Returns a vector of axis sizes	shape