MATLAB: Function to chop a decimal to a variable number of digits

arithmeticchoppingdecimalformat

I wrote the following function to approximate a number using chopping arithmetic. 
chop(5,4.333352312) 
function output = chop(numdigits,float)
y = floor(log10(float)+1); %number of digits in the integer part 
x = fix(numdigits - y); 
fprintf("%.xf",float) 
end
The function is meant to approximate a float using numdigits chopping arithmetic. Since that is a variable, the number of digits after the decimal point is unknown. The output in the above example should be 4.3333 but the output is 4e+00. Is there any alternate way to display a variable number of digits after the decimal point?

Best Answer

You can use an asterisk * to refer to an input of fprintf, so in your case all you need is:
fprintf("%.*f\n",x,float);
and tested:
>> chop(5,4.333352312)
4.3334
Of course if you want to return that string as an output argument you will need to use sprintf instead:
function s = chop(numdigits,float)
y = floor(log10(float)+1);
x = fix(numdigits - y);
s = sprintf("%.*f",x,float);
end
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