How to resolve problem in for loop?

a=java.math.BigInteger(100)

for i=1:a

a*a;

end

Undefined function '_colonobj' for input arguments of type 'java.math.BigInteger'.

Any help in this regard is much appreciated. Thanks

Answer 1

[John D'Errico]

Is "a" a number, in the form MATLAB will expect it? NO! a is a BigInteger number. You cannot use the colon operator on a.

a=java.math.BigInteger(100)

a =

100

whos a

  Name      Size            Bytes  Class                   Attributes

  a         1x1                    java.math.BigInteger              

So you could have used a loop like this:

for i = 1:double(a)

As far as the actual loop goes, What do you think this

a*a;

Operator '*' is not supported for operands of type 'java.math.BigInteger'.

does? NOTHING. Well, it does something. It throws an error. Because again, multiplcation is NOT supported in MATLAB between java.math.BigInteger objects. And even if it was supported, it would do nothing useful in MATLAB, just dumping the result into the bit bucket.

Anyway, if you want to multiply BigInteger numbers, the Java toolbox provides such a tool. Admittedly, it is a bit of a pain in the neck. This is why I put my own wrapper around those tools for use in MATLAB.

[Ammy]

Thank you very much.

a*a;

Yes you are right, actually it is

a.multiply(a)

[Image Analyst]

@Ammy yes, but the value won't be saved because you didn't assign the product to any variable. So, because you left off the semicolon, it will print the value to the command window -- that's all. Maybe that's all you want - I don't know.

a=input('Enter a : ');
for k = 1 : a
    result(k) = a * a;
end
result % Show all results in command window.

[John D'Errico]

Lol. You are wasting your time.

Do you understand how big is that number?

log10(2589665665565686656656)

ans = 21.4132

Over two sextillion.

Not much smaller than Avogadro's number. You want to loop THAT many times?

Are you running that loop on a super computer the size of the earth? Lets see. If you can run one billion loops per second, as I recall, there are roughly 31 million seconds in a year. So that will still take on the order of 85000 YEARS to finish the loop.

Are you a bit of an optimist? Or do you just have plenty of time to kill? Maybe you want to re-read the complete works of Shakespeare a few quadrillion times while you wait for it to finish?

[Ammy]

@John D'Errico thank you very much for explanation I got your point, thank you very much.