If the document opened in the IFRAME does not have any targets set, then all those links will open in the same iframe as the parent document. You can use this feature to make links in one IFRAME change the contents of another IFRAME on the same page. IFrames and Security. The IFRAME element, by
Sigma notation, often referred to as summation notation, can be used in many common situations. For example, it can be used to calculate the sum of deposits for a bank account. Banks add together all deposits and withdrawals to determine the current balance.
A shorter way of writing this is to let ur represent the general term of the sequence and put Xn r=1 ur. Here, the symbol Î£ is the Greek capital letter Sigma corresponding to our letter âSâ, and refers to the initial letter of the word âSumâ. So this expression means the sum of all the terms ur where r takes the values from 1 to n. We can also write Xb r=a ur to mean the sum of all the terms ur where r takes the values from a to b. In such a sum, a is called the lower limit and b the upper limit. Key Point The sum u1 +u2 +u3 +...+un is written in sigma notation as Xn r=1 ur. c mathcentre July 18, 2005 2