Message box

Both Fourier transform commands perform a Fast Fourier Transform (FFT) on the FID. If a baseline correction has not yet been performed on the raw data, a message box will appear which provides the option for performing a baseline correction (see section 5.3.3) on the time domain data (FID) prior to Fourier transformation. 

When the phase correction has been completed, click the Accept button and a message box appears on the screen. If Yes is selected then the xf2p command is executed and the F2 phase corrected spectrum will be calculated and shown on the screen. If No is selected the new values of the PHCO and PHCl parameters are stored for future use but no phase correction is performed. 

Figure 1.2 Screen displays during the activation of the Ih.xls GT Calculator file. Note that all the message box windows in the calculator are modal and so take precedence over the background display. Remember to check that the security level is set to medium in a blank EXCEL file before opening the calculator files, otherwise this opening sequence will not appear and the option to enable macros is not given.

To use the Solver, choose Solver... from the Formula menu. First you may see displayed the message box shown in Figure 12-2. This is only an advisory message, not an error message. Press OK. The Solver Parameters dialog box (Figure 12-3) will then be displayed. 

MsgBox returns a value that indicates which button was pressed. This allows you to take different actions depending on whether the user pressed the Yes, No or Cancel buttons, for example. To get the return value of the Message Box, use an expression like... 

That is all. SolverAid will place the values for the standard deviations of the parameters to the immediate right of those parameters if there is free or over-writable space there otherwise it will present the results in the form of a series of message boxes. SolverAid will also provide the standard deviation of the dependent variable, in the cell to the right of SRR. 

You should now see a message box that contains the text The cell value is followed by the value read. For example, if you highlight a cell that contains the value 3.456, then the message should read The cell value is 3.456 . If you select a cell containing the formula = SQRT(9) + 1.7you should see The cell value is 4.7 , and so on. 

The message box insists on being acknowledged, i.e., you must click on its OK button before you can do anything else in the spreadsheet. 

Try the modified macro. When you select an empty cell, the message box will report that it is empty, and thereafter the macro will add 4 to that value, to give the cell the value 4 when you repeat the process with the same cell, the macro will up the ante to 8, then to 12, and so on. 

Try to fool the macro by entering a letter, word or sentence. The message box will return the correct address, but will not be able to distinguish between a value and a formula. Instead, in both cases it will merely repeat the text it finds. 

Test this macro on an array of formulas, numbers, or text (i.e., one or more letters, words, or sentences). Observe thatitwill return the address range whether the cells involved are empty or not. It will return no information for the value or formula of an empty cell (but that it comes up empty-handed will stop neither the program nor the computer), and it obviously will not be able to distinguish between a value and a formula when a cell merely contains a number, or text. Still, where there is valid information to be had, the macro will read it properly, and the message boxes will report it. 

The following macro demonstrates an even more extensive use of message boxes, and a simplification in that only one Array is used, which can then be examined Item by Item. (Note again that VBA considers everything to the right of an apostrophe as a comment. For short instructions and comments, writing the comments to the right of the instruction leads to compact yet very readable code.) Enter this macro and test it on a small sample array. 

You will recognize that both message boxes accomplish the same purpose, the only difference being that the second is somewhat more elaborate, with a title and a question mark. Chr(13) is the character code for a linefeed, so that the message appears on two lines. The general syntax of a message box can be either... 

As our next example we use the input box to specify a single address, then verify that the address was read correctly by displaying it in a message box. When an input box is used to read either a single address or an address range of a multi-cell array (a block), preface the InputBox instruction with the command Set, and use Application, before InputBox. Then use that address to select the range, as in... 

The address can be entered either as text, or by highlighting the cell involved with the mouse pointer. In the latter case it may be shown in the message box in so-called row-column notation, as in R3C7 for row3 column 7, i.e., G3. Note that Type = 0 will read a formula, Type = 1 a number, Type = 2 a text string, Type = 4 will yield a logical value (True when the address contains a number, False when it is empty or contains a zero), Type = 8 will read a cell reference as a Range, and Type = 64 will read an array. 

In our example we will assume that the x- and y-values are stored in columns on the spreadsheet. We will read them separately, so that those columns need not be adjacent to each other. We will therefore use three input boxes, one each to enter the x-values, the y-values, and the specific x-value for which we want to interpolate the data. We will use a message box to display the resulting y-value. 

Now switch back to the spreadsheet, deposit a few numbers in a column, call the macro (with Tools O Macro, followed by clicking on the name of the macro and, then, on Run) and verily that the message boxes indeed display the correct addresses and their contents. The actual reading takes only three lines of code (or four, when we count as two the continued line following the space plus underscore) the other lines are there merely to make sure that the input box works properly. 

After we have satisfied ourselves that the input box works (either by outlining the range on the spreadsheet, or by typing it in the window of the input box as, say, B3 B7) we add a few lines to make sure that only a single column is selected. We accomplish this with an End statement inside the If-Then loop the End statement is reached only when the number of columns, NC, differs from 1. The message box just before that End statement specifies the nature of the problem. Make sure that this part also works, and only then delete the verification lines to obtain... 

Once more, verify that this code works, including those situations where the macro shuts down. After you are satisfied that everything works, remove the message boxes that display the values of XX and NClosest the other message boxes should of course stay. 

Putting all this together, with a few comment lines, and a message box for the final result, yields the following working macro ... 

The data output section is rather straightforward, except that we use the information whether there are data next to F. In that case, the answer is presented in a message box otherwise it will be written next to F. 

When the input data are in columns (or rows), the standard deviation of the single function F will be placed directly to the right of (or below) that function, in italics, provided that this cell is either unoccupied or its contents can be overwritten. Otherwise, the result will be displayed in a message box. 

The program tests whether any of the cells that will be used for the output are free of contents. If not, the user is asked whether or not to proceed with the transform. If the answer is no, the program is halted, to give the user time to free the output space while saving its contents. Note that the linefeed character Chr (13) is used to divide the text in the message box into two parts of near-equal length. 

A message box is primarily used to provide textual and/or numerical information to the user it can also carry logical information back to the program that issued it. Message boxes figured prominently in sections 10.1 and 10.2. In their most basic form they have the syntax... 

Apart from their obvious uses in finished macros and subroutines, message boxes are convenient during program development for debugging, by displaying intermediate parameter values, and for enforcing a pause in program execution. 

Input boxes are meant to provide textual and/or numerical information to the program. Apart from a prompt, as in the Message Box, they also have a window, in which information can be typed. Several examples were already given in section 10.2. The syntax for the input box. function is... 

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