How to avoid If statement?

Hi,

I have a few lines of code like this:

  if(volTbl.ReturnType(k) == 1)
    logR = diff(log(abs(newtable.price)));
  else
    logR = diff(newtable.price);
  end

I would like to avoide the if statement because the tables are large and the calculation is intensive. How to do that? Thanks a lot.

Jennifer

[Image Analyst]

How large? Like hundreds of millions of elements?

And it's not the "if" that's taking up the time, it's the diff(), and log(). Is this code in a loop over many millions of iterations? Or is it just a one time calculation?

[JFz]

Thanks. yes, you are right. It is indeed in a large for loop.

Answer 1

[Walter Roberson]

selectfun = @(cond, tf_funs, x) tf_funs{cond+1}(x);

logR = diff( selectfun(volTbl.ReturnType(k) == 1, {@(x) log(abs(x)), @(x) x}, newtable.price) );

This does not use "if", but I suspect it will be slower than if you used "if".

To get much performance improvement you would need to be writing to a different result location for each "k", such as if the statement were logR(k,:) = ... and you would need a different input location for each, such as newtable(k).price, and you would need to be doing a whole series of "k" values. But when your input is always the same and your output is always the same and you are only doing one "k" value, then it is difficult to get faster than "if".

[JFz]

Thanks! Let me try it.