Variables
Wed, 09/02/2009 - 11:44
#12
Even better, but probably harder to code is a cut and past that would let you take the entire formula. You could paste one equation into the other ie. sigma=Mc/(pi*r^4)/4.
Actually, it's technically easier to do this, which is something I'm working on. It probably won't be in the next update, but I should have full copy-and-paste support of equations and elements of equations within the next few months.
Wed, 09/09/2009 - 17:12
#13
I think I'm still missing something. I created a saved equation with a bunch of variables:
0.5 rho pi/4 D^2 V^3 = P
now when I'm ready to use it I click on it in my saved library but when it displays it in the main window an x has been substituted into the first position like
x rho pi/4 D^2 V^3 = P
I don't know why it substituted an x for the number 0.5 or the proper method for now substituting values for each of the real variables
Tue, 09/15/2009 - 10:17
#14
I think I'm still missing something. I created a saved equation with a bunch of variables:
0.5 rho pi/4 D^2 V^3 = P
now when I'm ready to use it I click on it in my saved library but when it displays it in the main window an x has been substituted into the first position like
x rho pi/4 D^2 V^3 = P
I don't know why it substituted an x for the number 0.5 or the proper method for now substituting values for each of the real variables
0.5 rho pi/4 D^2 V^3 = P
now when I'm ready to use it I click on it in my saved library but when it displays it in the main window an x has been substituted into the first position like
x rho pi/4 D^2 V^3 = P
I don't know why it substituted an x for the number 0.5 or the proper method for now substituting values for each of the real variables
I think what might be happening here is that the 0.5 numerical value was not a pure number, but was a value that had been filled into an x variable. Right now, I default to saving the variable, but not the numerical value that has been filled into it. I'll probably change this behavior in the next update.
Sorry for the confusion.
Sun, 09/20/2009 - 00:42
#15
You are right. It was an x variable. Don't know how I did that but when trying to edit it and make it a numerical value I couldn't seem to get it to change the type from x variable to numerical value so I ended up deleting the entire initial element of the equation and recreating it. I think you should keep the default saving the way it is, but perhaps make editing it to change it's type a little easier.
Second related issue. If I understand right, when I want to use a saved equation the proper method is to just click on each variable in the selected saved equation and type in the numerical value I want to use in this calculation. A couple minor thoughts and 1 major:
1. It would be nice to be able to set defaults for the precision of the answer rather than automatically seeing around 15 digits in the answer.
2. It would be nicer to have a list of variables to assign numerical values to above the equation rather than selecting and substituting for each one directly in the equation. Maybe only my personal preference.
3. Major comment: I'd really like to be able to input a string of numerical values to create an array of solutions. I know you can export the equations to a graphing program, but how about some functionality relatively simple borrowed from matlab like 0:1:10 for the integers 1 to 10.
thx
ed
Sun, 09/20/2009 - 15:56
#16
I think you should keep the default saving the way it is, but perhaps make editing it to change it's type a little easier.
Yes, it can be a little confusing the way it is right now. I'll see if I can think of a better way of handling that.
1. It would be nice to be able to set defaults for the precision of the answer rather than automatically seeing around 15 digits in the answer.
I'm working on a way to specify this, which will be needed to make numerical units on answers practical.
2. It would be nicer to have a list of variables to assign numerical values to above the equation rather than selecting and substituting for each one directly in the equation.
This was how I was going to handle variables originally, but the interface ended up being too crowded. I might do this on versions of this application running on larger screens (Mac or rumored tablet), and I'll see if I can make it practical for the iPhone.
3. Major comment: I'd really like to be able to input a string of numerical values to create an array of solutions. I know you can export the equations to a graphing program, but how about some functionality relatively simple borrowed from matlab like 0:1:10 for the integers 1 to 10.
I don't know how many people would use such a capability, given how difficult it would be to implement, interface-wise. Again, this might be better suited to a desktop client, rather than an iPhone application.
Thu, 09/24/2009 - 03:53
#17
I like the string idea and just got this progam. It's great! Now that you have the variable /custom equation thing worked out you need a custom equation sharing and rating mechanism. Most of the custom equations peoplare using are just standard equations from other fields, like acoustics in my case. Then allow for detailed explanations so people can share knowledge or even come up with entertaining or mathmatical hypotheses to be tested out for the hell it, sharing results.
This program is cool.
Thu, 09/24/2009 - 09:58
#18
Really cool idea. A social calculator. Awesome.
Mon, 12/28/2009 - 12:11
#19
I just downloaded the app and I think you are right on target with creating a iPhone/iTouch tailored calculator. Emulating calculators is soooo 20th century. And HP is charging $30 for an emulator of their 1980's calc!
Having said that, it appears that the Pi^3 is missing a key feature of the old calcs; a memory capability. I have read the documentation and the forums and it still appears that variable store capability is still in the works?
Have you considered adding another menu item to the 'Variables and constants menu'; x | pi | e menu? So it would look something like x | pi | e | M? Pressing M would bring up an area similar to the saved equation page but have stored values to choose from. And on the right side equation part, have a check box (or something) that says store to memory?
Not sure it is practical or makes sense. Just early morning thoughts.
Thu, 12/31/2009 - 14:57
#20
Anyone knows if the operator ABS (Absolute) exists?
Love the app, cant wait for updates. The following is a suggestion I would imagine useful for future release (if possible).
Is it possible to make variables passed, and have the application function in the following manner?
Assume you are working with an equation like: sigma = Mc/I
When you click the "I" variable an option to load an equation or constant exists. By choosing the equation or constant, you are given an option to either solve or insert the linked choice in the variable field. Assume I was interested in the area moment of inertia of a circle. (pi*r^4)/4=I. At r=.25, I=.000306.
When this sub formula is solved the answer can be passed back to the equation. The equation now reads
sigma=Mc/.000306
Even better, but probably harder to code is a cut and past that would let you take the entire formula. You could paste one equation into the other ie. sigma=Mc/(pi*r^4)/4.
I think this type of approach would shed a lot of insight into variable relationships, and sensitivity in respect to the mathematical problem.