Plot graph of polynomials

Question

Yash Raj Sitaram Prasad 2021-9-9

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1449914-plot-graph-of-polynomials

回答： Yash Raj Sitaram Prasad 2021-9-10

采纳的回答： John D'Errico

I want to plot graph of polynomial function such as

|x| and many more like this.

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Answer 1

John D'Errico 2021-9-9

1
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https://ww2.mathworks.cn/matlabcentral/answers/1449914-plot-graph-of-polynomials#answer_784019

在 MATLAB Online 中打开

That is not a polynomial.

You have a sqrt root in there. And an absolute value. So learn how to use functions like abs, and sqrt. You will not learn unless you try.

help abs
 ABS    Absolute value.
    ABS(X) is the absolute value of the elements of X. When
    X is complex, ABS(X) is the complex modulus (magnitude) of
    the elements of X.
 
    See also SIGN, ANGLE, UNWRAP, HYPOT.

    Documentation for abs
       doc abs

    Other functions named abs

       codistributed/abs    duration/abs    iddata/abs    sym/abs
       dlarray/abs          gpuArray/abs
help sqrt
 SQRT   Square root.
    SQRT(X) is the square root of the elements of X. Complex 
    results are produced if X is not positive.
 
    See also SQRTM, REALSQRT, HYPOT.

    Documentation for sqrt
       doc sqrt

    Other functions named sqrt

       codistributed/sqrt    dlarray/sqrt    gpuArray/sqrt    sym/sqrt

First, you would you need to create such a function.

F = @(x) sqrt(abs(x));

Then to plot a function like that, you might read about fplot.

help fplot
 FPLOT   Plot 2-D function
    FPLOT(FUN) plots the function FUN between the limits of the current
    axes, with a default of [-5 5].
 
    FPLOT(FUN,LIMS) plots the function FUN between the x-axis limits
    specified by LIMS = [XMIN XMAX]. 
 
    FPLOT(...,'LineSpec') plots with the given line specification.
 
    FPLOT(X,Y,LIMS) plots the parameterized curve with coordinates
    X(T), Y(T) for T between the values specified by LIMS = [TMIN TMAX].
 
    H = FPLOT(...) returns a handle to the function line object created by FPLOT.
 
    FPLOT(AX,...) plots into the axes AX instead of the current axes.
 
    Examples:
        fplot(@sin)
        fplot(@(x) x.^2.*sin(1./x),[-1,1])
        fplot(@(x) sin(1./x), [0 0.1])
 
    If your function cannot be evaluated for multiple x values at once,
    you will get a warning and somewhat reduced speed:
        f = @(x,n) abs(exp(-1j*x*(0:n-1))*ones(n,1));
        fplot(@(x) f(x,10),[0 2*pi])
 
    See also FPLOT3, FSURF, FCONTOUR, FIMPLICIT, PLOT, FUNCTION_HANDLE.

    Documentation for fplot
       doc fplot

So you might do this.

fplot(F)