Problem 10. Determine whether a vector is monotonically increasing

I think test 2 is wrong. Is x=0 monotonically increasing? I think not.

I think test 2 is wrong. Is x=0 monotonically increasing? I think not. Why is assertion made against true then?

Does anyone know why this is not working? The code looks chunky, but it should work. Thanks!!
string1 = ['tf is true'];
string2 = ['tf is false'];
tf = diff(x);
w = numel(find(tf==0)) + numel(find(tf<0));
if w > 0
disp(string2)
else
disp(string1)
end

[0] is monotonically increasing, but [0 0 0 0 0] is not. That's messed up. I agree with Kye Taylor.

All solutions with size 11 use the regexp cheat.

[0] isn't going anywhere by definition. It makes no sense that it's 'increasing'.

I agree that [0] should give false by this function, it's not monotonically increasing or increasing at all, right? I also think the test suite should include some vector like [-1 2 3 3] that is sorted but not mon. increasing.

Monotonically increasing means that it is never strictly decreasing. [0] is monotonically increasing for this reason, as is any constant vector. This problem should be restated as: Determine if the vector x is "strictly" increasing.

Nice one :D

between 'monotonic' and 'strictly' increasing.

good

Test 3 is incorrect isn't it? By definition, the following is monotonic, and hence also monotonically increasing:
x = [0 0 0 0 0];

One easily understandable size 15 solution is (use rot13 to read it):

shapgvba gs = zbab_vapernfr(k)
gs = vfrdhny(k, havdhr(k));
raq

nice

Good question

for i= 1:(length(x)-1)
if (x(i)< x(i+1))
disp('true');
else
disp('false');
end
end
it is providing correct result in my pc but not accepting here

@Sankari Name, Dawg, replace "disp('false')" and "disp('true')" with "tf=false" and "tf=true" respectively. see below,

x=[0]
for i= 1:(length(x)-1)
if (x(i)< x(i+1))
tf=true
else
tf=false
end
end

but your code wont pass the test where x=[0]

The [former] second test case of x = [0] has been removed due to its tendency to cause confusion.

Also, the test case with x = [0 0 0 0 0] has been removed since it was originally marked as false. Technically, a monotonic function "is either entirely nonincreasing or nondecreasing" per Wolfram.com. Per this definition, that answer should have been true, as it would also be true for monotonically decreasing.

nice

can someone explain to me why this code is not good for this problem

function tf = mono_increase(x)
for i:1:(length(x)-1)
if x(i+1) > x(i)
tf = "true"
else
tf= "false"
end
end
end

@Ongun Palaoglu:
#1, you are returning strings of true and false instead of true or false values. Do not use " in the solution.
#2, you are returning a true or false value for each comparison, with each prior result being overwritten. Only the last value will be returned by the function.

Single line solution.

a little bit difficult

function tf = mono_increase(x)
tf = false;
for ii=2:length(x)
if x(ii-1)< x(ii)
tf=true;
end
end
end

why i have 2 assertion errors i don't get it?what i's wrong

@Gizem, because your code only a partial condition of what is asked.

interesting one

basic algebra question.

I can't use diff function becasue it contain 'if'. What the hell

@Xingkai, that issue has been resolved and your solutions have been rescored.