Error using cos.Not enough input arguments.

Question

Cristian Rosca 2020-9-4

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/588994-error-using-cos-not-enough-input-arguments

评论： Fangjun Jiang 2020-9-4

采纳的回答： Fangjun Jiang

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Hi all,

Can anyone help me with this problem - Error using cos Not enough input arguments.

  A2=sinh((x^2)+cos^2*y)^3/sqrt(abs(x-cos(y))+ln*(abs((x-cos(y)))/(x^2)+(cos^2)*y+abs(sin)*x))
Error using cos
Not enough input arguments.

i am new to matlab and i need to rezolve these expresition.

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Stephen23 2020-9-4

编辑：Stephen23 2020-9-4

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The function cos requires one input argument. As the error message states, you have called cos with no input argument, which throws an error. I have marked those locations for you, showing where you have called it incorrectly:

A2=(sinh((x^2)+(cos^2)*y)^3/sqrt(abs(x-cos(y)))+ln*(abs((x-cos(y))))/(x^2)+(cos^2)*y+abs(sin(y))*x)
%               ^^^^                                                        ^^^^

Your use of matrix operations is also quite likely to be incorrect:

https://www.mathworks.com/help/matlab/matlab_prog/array-vs-matrix-operations.html

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Answer 1

Fangjun Jiang 2020-9-4

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try this line by line

y=pi
(cos(y))^2
cos^2*y

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Cristian Rosca 2020-9-4

编辑：Cristian Rosca 2020-9-4

when x=-1.75*10^-3

y=3*pi

Fangjun Jiang 2020-9-4

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create some interim variables and build up your result

x=-1.75*10^-3;
y=3*pi;
cos_y=cos(y);
temp1=x^2+cos_y^2;
temp2=x-cos_y;
A2=sinh(temp1^3/sqrt(abs(temp2)))+log(abs(temp2/temp1))+abs(sin(y))*x

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Answer 2

Steven Lord 2020-9-4

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In mathematics we write

but when we implement that in MATLAB we implement it as

[not to be confused with

.]

x = pi/4;
y = cos(x)
z = cos(x).^2 % compare to y^2
w = cos(x.^2)

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Steven Lord 2020-9-4

Run those four lines. See that z is the square of y. That is how you compute the square of the cosine of an angle. cos^2(x) is not valid MATLAB syntax.

Cristian Rosca 2020-9-4