USer Defined Function problem

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A M Saif Ben Kabir Amit
编辑： Ameer Hamza 2020-4-21
Write a user-defined MATLAB function named PBTask4p1_f.m for the following math function with x the input argument and y the output: ?(?) = 3.2? 4 − 5? 2 − 7? The function should work for x being a scalar or a vector.
Use the function to calculate y(-5) and y(4) and display the results in command window b) Use the function to make a plot of the function y(x) for -5 ≤ x ≤ 5. Label the x-axis and y-axis of the plot like the one as follows.
I am new at Matlab ,Any help would be appriciated.Thank you
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Ameer Hamza
Ameer Hamza 2020-4-20
What does not work? What is the error? Also, you function only need output 'w', why have you put 'z' in the output arguments.
A M Saif Ben Kabir Amit
A M Saif Ben Kabir Amit 2020-4-20
编辑：Ameer Hamza 2020-4-20
function w=PBTask4p1(x)
w=3.2*x^4-5*x^2-7^x
end
PBTask4p1_f(-5)
w =1.8750e+03
ans =1.8750e+03
>> PBTask4p1_f(4)
w =-1.6618e+03
ans =-1.6618e+03
I got these output after removing the z from output.
Now how can I plotfrom this instruction (Use the function to make a plot of the function y(x) for -5 ≤ x ≤ 5.)
Thank You
>>

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Ameer Hamza
Ameer Hamza 2020-4-20
Since you have already written the function, let me give you some information. In MATLAB '*' is used to indicate matrix multiplication. To do scalar multiplication, change the '*' operator in your code to '.*'. Like this
function w=PBTask4p1(x)
w = 3.2.*x.^4 - 5.*x.^2 - 7.^x;
end
Then create a vector of x values. Some thing like this
x = -5:0.1:5;
The use this x as input to PBTask4p1 and save the output in a variable. And then you can use plot() function
plot(x,w)
to create a plot.
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A M Saif Ben Kabir Amit
A M Saif Ben Kabir Amit 2020-4-21
Ok I got it now.Thank You for your kind help.

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