Điều này sẽ trả về giá trị lỗi # VALUE! Có một số điều kiện dẫn đến giá trị này. Chúng tôi đã trôi qua không phải số đối số (các tế bào A3, B3, C3 chứa văn bản) một chức năng mong đợi giá trị số. Lỗi này cũng có thể được gây ra bởi một lỗi cú pháp trong chức năng. | 154 A Guide to Microsoft Excel 2002for Scientists and Engineers b On Sheet4 of enter the text and values in AI D3 of Figure and the values in A4 C7. In D4 enter RootCount A4 B4 C4 and copy it down to row 7. The values in column D should agree with those in Figure . c Constant values may be used as arguments. To demonstrate this move to an empty cell such as A10 and enter RootCount 1 -5 6 . This should return the value 2. d Move to an empty cell such as All and enter RootCount A3 B3 C3 . This will return the error value VALUEl. There are a number of conditions that result in this value. We have passed non-numeric arguments the cells A3 B3 C3 contain text to a function expecting numeric values. This error can also be caused by a syntax error in the function. Exercise 7 The Structure In a looping structure a block of statements is executed repeatedly. When the repetition is to occur a specified number of times the structure is used. The syntax for this structure is given in Figure . Microsoft Excel provides the function FACT to compute n factorial. For example FACT 4 returns the value of 4 1 X 2 X 3 X 4. In its absence we could have coded such a function using a FOR loop Function Fact n Fact 1 Forj 1 to n Fact Fact j Next j End Function. When the loop is first entered j is given a value of I. The statement Fact Fact j may be confusing at first. Remember that computer code statements are instructions not mathematical equations. This statement may be read as the new value for Fact is its old value multiplied by 1. The Next statement increments increases by 1 and sends the program back to the loop. Another new value of Fact is computed as Fact 2. These steps are repeated until j is greater than the argument n at which point the program continues to the line following the Next statement. The reader should see that the function would be slightly more efficient if the third line read For j - 2 to n. User-defined Functions 155 Syntax
