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# Signal and system = convolution: Matlab i need help with the

### Customer Question

Signal and system = convolution: Matlab
Hi,
i need help with the question attached, please
Submitted: 4 months ago.
Category: Homework
Expert:  Bruce Wilner replied 4 months ago.

As is so often the case, there is no question attached. Otherwise, I would be thrilled to help.

Customer: replied 4 months ago.
Sry, I didn't know how to add the files.... the question is attached in the problem
Customer: replied 4 months ago.
I mean in the pictures
Customer: replied 4 months ago.
this instructions may be helpful in solving the problem:The CONV commandConv(x, h) returns the convolution sum of the vectors x and h. When using this command, one must compensate for the fact that MATLAB only allows vectors to be indexed from 1. When the input vectors have values for n < 1 (i.e. x[0], x[-1], etc.), you must keep track of the vector index that you associate with the value at x[0] (call this the zero'th position of vector x). When computing the convolution sum of two vectors, the zero'th position in the output vector (i.e. the position in the output vector that corresponds to y[0]) can be found using the following equation:zy = zx + zh - 1where zy is the position of the output vector, and zx and zh are the zero'th position of the input vectors. Consider the following example:x[n] = [0, 0, 1, 3, 2, 3, 1, 0, 0]
h[n] = [0, 0, 0, 1, 1, 2, 2, 0, 0, 0]where the bold font marks the zero'th position (i.e. x[0] = 3, h[0] = 0). The following MATLAB program defines x and h, and computes y = x * h.>> x = [0 0 1 3 2 3 1 0 0];
>> h = [0 0 0 1 1 2 2 0 0 0];
>> y = conv(x, h);The zero'th index of vector x is 4 since x[4] corresponds to the value of vector x at n = 0. Likewise, the zero'th index of vector h is 1 since h[1] corresponds to the value of vector h at n = 0. The zero'th position of the output vector y is calculated to be 4 in this case.Adjusting your plots to display the correct x axisTo plot y with the time axis correctly adjusted, one shifts the x axis to the right by four (i.e. subtracting 4 from the values in the x axis). This can be done by supplying an additional parameter to the 'stem' or 'plot' command:>> stem (-3:(length(y)-4), y);
{plots y with the time axis correctly compensated}Note that -3:(length(y)-4) was determined by subtracting 4 from the value of the first index of y (i.e. 1 - 4 = 3) and from the value of the last index of y (i.e. length(y) - 4). Note also that stem and plot both require that the given range is the same 'size' as the vector to be plotted (i.e. size(-3:(length(y)-4)) = size(y)). Adjustments like the one made above are common in MATLAB since all vectors are indexed starting from 1, so you should pay attention to the x axis every time you make a plot.
Expert:  Bruce Wilner replied 4 months ago.

All of those problems?

Customer: replied 4 months ago.
it's problem consist of multiple parts
the first three are basic i just don't have time to spend on it
Customer: replied 4 months ago.
i believe mostly every part is 5-7 commands i just don't know what commands to use
Customer: replied 4 months ago.
Just to make sure, so you are going to work on it? thanks
Customer: replied 4 months ago.
I want to cancle my order