There are numerous errors in the code, the condition on the if statement makes no sense I assume you mean:
if r(i)>=minval & maxval<=r(i)
The for loop syntax is invalid, I assume you mean
for i=1:1:length(r)
These lines in the alternative conditionals are invalid syntax (and even if they were valid I have no idea what their purpose is) - maybe a filter to omit out of range values from the input vector? If this is the case it wouldn't work - you would be better off building a new vector containing valid values, rather than delete values from the existing vector since this will make the vector smaller and lead to an indexing error as the loop progresses through the vector.
r(i)=(); %maybe you mean r(i)=[], but this wouldn't work in the context of this program
