Maximum value in a vector
显示 更早的评论
Problem statement: Use the max function to find the value and location of the maximum y value. Use fprintf to show the maximum y and the x value for which it occurs. When I use the max function it always returns -1?
x = [linspace(-pi,pi,10)]
n = [length(x)];
for i = 1:n
fprintf(' %.0f: %f ', i, x(i))
end
for i = 1:n
y = [cos(x(i))];
fprintf(' %f ',y)
end
max(y)
采纳的回答
The problem is that you don't have a vector, although you think that you do. Actually y is a scalar value -1, so of course min(-1) will give you that output. This happens because you simply reallocate y on every loop iteration, so at the end of the loop it only has the last value. You could use indexing to fix this.
A much better way to solve this problem is entirely without loops:
>> X = linspace(-pi,pi,10);
>> Y = cos(X);
>> [maxY,idx] = max(Y);
>> maxX = X(idx)
maxX = -0.34907
>> maxY
maxY = 0.93969
Loops are often an inefficient way of solving problems in MATLAB.
3 个评论
NT
2016-3-23
Stephen23
2016-3-23
Like I said: use indexing to store the y values in the loop. Then apply max after the loop. Indexing is covered in thousand of tutorials online, so you won't have any problem with that.
sunil shetty
2019-5-17
Hi ,
Is this solution applicable for 2D or 3D vector ?
Thanks & Regards ,
Sunil
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