2016년 12월 30일 금요일

Problem with converting Grads to Degrees

I just started my trip with MIT AI2. I'm trying to do some Geodesy tools to help my friends on geodesy studies.
Okay, but back to the topic. I have some problems with conversion Grads to Degrees. They are both angle measuers but in degrees we have 360 degrees, 60 minutes and 60 seconds, and in grads we have 400 grads, 100 centygrads and 100 myriograds.
Firstly, how do you can enter a maximum number (eg 100)?
Secondly, how to do if the result shows a number greater than the maximum number of minutes (60) added to the previous field (degrees) one degree, and take away the minute appropriate value?

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Firstly, how do you can enter a maximum number (eg 100)?

after entering some data, then do some data validation using an if statement

if entered data > 100
then display a message "max. value is 99"
else do the calculation

Secondly, how to do if the result shows a number greater than the maximum number of minutes (60) added to the previous field (degrees) one degree, and take away the minute appropriate value?

you might want to prepare an example of a conversion and how the correct result would look like, also the formula of the calculation probably can help us to help you

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Ok second thing I already did by if/then/else :) But i have problem still with first.
It's hard to do, because:
1) i cant find display a message,
2) i have 3 different text box and i think it will be impossible to display 3 messages at once

I think about formula that you cant type in text box more than eg 360, 60 etc

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use a notifier component

if textbox1 > 100
then Notifier.ShowAlert "textbox1 must be < 100"
else if textbox2 > 360
then Notifier.ShowAlert "textbox2 must be < 360"
else if textbox3 > 60
then Notifier.ShowAlert "textbox3 must be < 60"
else do the calculation

A very good way to learn App Inventor is to read the free Inventor's Manual here in the AI2 free online eBook   http://www.appinventor.org/book2 ... the links are at the bottom of the Web page.  The book 'teaches' users how to program with AI2 blocks.
There is a free programming course here http://www.appinventor.org/content/CourseInABox/Intro  and the aia files for the projects in the book are here:  http://www.appinventor.org/bookFiles
How to do a lot of basic things with App Inventor are described here:  http://www.appinventor.org/content/howDoYou/eventHandling  .

Also do the tutorials http://appinventor.mit.edu/explore/ai2/tutorials.html to learn the basics of AppInventor, then try something and follow the

You will not find a tutorial, which does exactly what you are looking for. But doing the tutorials (not only reading a little bit) help you to understand, how things are working. This is important and this is the first step to do.

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THANK YOU VERY MUCH! You are incredible!

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