fsurfht

R2026b

Interactive contour plot of function

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Syntax

fsurfht(fun,Xlims,Ylims)
fsurfht(fun,Xlims,Ylims,p1,p2,...,p5)
fsurfht

Description

fsurfht(fun,Xlims,Ylims) creates an interactive contour plot of the function specified by fun, with plot limits defined by Xlims and Ylims.

example

fsurfht(fun,Xlims,Ylims,p1,p2,...,p5) allows you to specify five optional parameters for the function fun.

example

fsurfht with no input arguments creates an interactive contour plot of the peaks function.

Examples

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Open Live Script

Create an interactive contour plot for the power function f(x,y) = xy. Specify the plot ranges [0.1 1] for x and [1 10] for y.

fsurfht("power",[0.1 1],[1 10])

Figure power contains an axes object and other objects of type uicontrol. The axes object contains 23 objects of type contour, line, text.

The Z Value box contains the value of the power function at the intersection of the dot-dashed crosshair lines at the center of the plot. Click the plot or enter values in the X Value and Y Value boxes to display the function value at a different location.

Open Live Script

Define a function named mytrigfun.m that returns a linear combination of two trigonometric functions.

Display the contents of the mytrigfun.m file.

type mytrigfun.m
function z = mytrigfun(X,Y,a,b,type)
    if type == "cos"
       z = a*cos(X)+b*cos(Y);
    else
       z = a*sin(X)+b*sin(Y);
    end
end

Create a contour plot of the function over the range –pi to pi for X and Y. Specify a = 2 and b = –3, and use a linear combination of sine functions.

fsurfht("mytrigfun",[-pi pi],[-pi pi],2,-3,"sin")

Figure mytrigfun contains an axes object and other objects of type uicontrol. The axes object contains 41 objects of type contour, line, text.

Evaluate z at the maximum by entering the values in the X Value and Y Value boxes shown below.

Contour plot with crosshair at maximum z value.

Input Arguments

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Prediction function, specified as the name of a built-in function that accepts two numeric scalar input arguments, or the name of another function on the MATLAB® path. The function must have this form:

z = myFun(X,Y,p1,p2,...,p5)

  • The output argument z is a numeric scalar.

  • You specify the function name (in this case, "myFun").

  • X and Y are numeric scalars.

  • p1,p2,...,p5 are optional parameters.

Example: fsurfht("power",[0.1 1],[1 4])

Example: fsurfht("myFun",[0 1],[1 10],"myoption",false)

Data Types: string | char

X-axis limits, specified as a two-element numeric vector [Xmin Xmax].

Data Types: single | double

Y-axis limits, specified as a two-element numeric vector [Ymin Ymax].

Data Types: single | double

Function parameters, specified as values of any data type. You can specify up to five parameters as inputs to the function specified by fun.

Tips

  • The intersection of the vertical and horizontal reference lines on the interactive plot defines the current x value and y value. Drag the reference lines to change the x and y values, and see how the function simultaneously updates the interpolated z value (at the top of the plot).

  • Alternatively, obtain a specific interpolated z value by entering the x value and y value into the labeled boxes on the x-axis and y-axis, respectively.

Alternative Functionality

You can also create a contour plot using the contour function, which offers greater functionality than fsurfht. For an example, see Contours of a Function. When you create a contour plot using contour, you can display information about the contour line values by setting datacursormode to "on" at the command line and then clicking a contour line in the plot.

Version History

Introduced before R2006a

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See Also

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