Need to define an array

I need an array that has 98 entries. the first value is 1000 and the second to last is 100. the values inbetween vary linearly but alternate with zeros.

[1000, 0, ~990,0.... 100,0]

[Stephan]

sounds like a homework. please provide your attempt so far.

[Thomas Holmes]

T=linspace(1000,100,49)
Fg=zeros(1,98)
for i=1:length(Fg)
    if mod(i,2)==0
        Fg(i)=Fg(i)
    else
        Fg(i)=T(i)
    end
end

This almost works but it does not replace Fg with the correct value of T.

How can i alter T or the index so that the 1st entry of T will be the first of Fg, then the 2nd entry of T will be the third entry of Fg leaving a zero between them.

[madhan ravi]

What?

Answer 1

[Stephan]

Hi,

note that the length of T is 49 - not 98.

The proper way to do this is:

Fg=zeros(1,98);
Fg(1:2:end) = linspace(1000,100,49)

Thats all.

Best regards

Stephan

Answer 2

[Jan]

@Thomas: The problem is still unclear.

"the first value is 1000 and the second to last is 100" - this means:

R = [1000, repmat(100, 1, 97)]

"the values inbetween vary linearly but alternate with zeros" - this is not clear: inbetween what?

The output should have 98 elements, while the first and the last is non-zero and the others are zero. This is not possible, because you need an odd number of elements for this.

You have shown some effort. So although I assume it is a homework, it is worth to assist you. Maybe all you want can be done in a single line:

Result(1:2:97) = linspace(1000, 100, 49);

But te result has 97 elements. There is no way for alternating zeros and non-zeros with leading and trailing non-zero and and even number of elements. Maybe with a trailing 0 (see Stephan's comment) pre-allocate the output at first:

Result = zeros(1, 98);

Or with your loop:

T  = linspace(1000, 100, 49)
Fg = zeros(1, 98);
for k = 1:length(T)  % Not length(Fg)
   Fg(k * 2 - 1) = T(k);
end

Again, the last element is 0 then.

[Stephan]

In his question the last element is a zero:

"...[1000, 0, ~990,0.... 100,0]"

[Jan]

@Stephan: You are right. The question is confusing and some feedback of the OP would be nice.