Round to specified decimal number?

How can I round a number to the nearest specified decimal value?

For instance round 3.7234234 to the nearest 0.25 multiple, so it would output 3.75.

[Keith Lewis]

Here is a solution based on Daniels link. Just added a test for whether to round up or down based on which is closer.

prompt={'Decimal to be rounded:','Decimal interval to round to'};
defaultans={'2.149','0.05'};
num_lines=1;
answer=inputdlg(prompt,dlg_title,num_lines,defaultans);

deimcalToRound=str2double(answer{1});
roundingInterval=str2double(answer{2});

up = roundingInterval*ceil(deimcalToRound/roundingInterval);
down = roundingInterval*floor(deimcalToRound/roundingInterval);

subup = deimcalToRound - up
subdown = deimcalToRound - down

asubup = abs(subup)
asubdown = abs(subdown)

if  asubdown < asubup
roundingInterval*floor(deimcalToRound/roundingInterval)
else
roundingInterval*ceil(deimcalToRound/roundingInterval)
end

Answer 1

[Daniel kiracofe]

this thread looks appropriate:

http://www.mathworks.com/matlabcentral/answers/14495-rounding-elements-in-array-to-nearest-0-25?s_tid=answers_rc1-1_p1_MLT

[Keith Lewis]

Thanks!