HP Prime - some strangeness I discovered with the solver

[@sketch7022]

I have the same set up , an hp prime with a remarkable, so far has work wonders in my math and language classes.

[@scottcollins7513]

The Remarkable is an interesting device. You are one of the few who recognize what it is.

[@Ioosks]

​Fsolve ​@@eraldo_c

[@claude77573]

Variables created by apps should be viewable if you press the Toolbox button and then select the Catlg tab. To see potential conflicts, where a symbol used by an app has been defined as a matrix entry, a list entry, a user vairable or a CAS variable, press Shift + Toolbox to bring up the Memory Manager.

[@scottcollins7513]

Good info (and well-beyond my familiarity w/ the Prime!). Thanks for leaving a comment - it may help someone out there.

[@pgaven9396]

How would someone do a function like say...input a formula into a column to apply into the next column. for example D2=D2^2 to make it actually calculate without giving an error message in 1 var stats?

[@scottcollins7513]

I am not following. D2=D2^2 will give an error b/c it is a circular formula. Note: Even if you clarify, there is a good chance I will still *not* know how to help due to my limited knowledge of the HP Prime. But, I will try if you want to give more info or examples.

[@pgaven9396]

@@scottcollins7513 well the ti84 for example you can input a formula in 1var stats and edit columns and then highlight the L2 and input a formula for the calculator to do calculations based off entries in the first column....on the L2 you would input L2 =L1-L2^2

[@pgaven9396]

@@scottcollins7513 i know its possible to do that but I haven't figured it out on the hp prime

[@scottcollins7513]

@@pgaven9396 kzbin.info/www/bejne/a5u9Z52Le86Ebck Not great quality, but shows the use of spreadsheet on Prime. Could you achieve your goals with this?

[@noahgrayhek1100]

@@pgaven9396 if I'm not mistaken you may have to do something like a loop: D2:=D2_old^2; D2_old:=D2; Then repeat however many times you need. You just replace the D2_old with the previous solution for D2 to solve for a new D2 referencing the previous solution. Does this help?

[@IonCubekhanz]

@Scott Collins plz make a video as to how to use matplotl python library provided in latest firmware

[@scottcollins7513]

IonCube, I think you just went over my head. I rarely use the Prime -- just never really "bonded" with it -- and I definitely am not a power user. I appreciate you making a suggestion, but it is outside of my expertise (if I have any at all!). Perhaps someone else will take you up on your offer. Best wishes.

[@eeemuse]

Hi Scott, do you know how to input a derivative to the second order (or nth order in general) on this calc? the one in the template is only 1st order.

[@scottcollins7513]

You can do a "nested" derivative. For example, if I wanted to find the 2nd derivative of y=x^3, I could put in the following: d{ d(x^3)/d(x) } / d{x} Sorry the formatting is not more flexible, but the idea is that for the numerator you are nesting in another d()/d() function.

[@scottcollins7513]

I did this in CAS mode and it gave the expected "6x" answer.

[@shaikhtissa6991]

I'm tryimng to solve a problem of the same nature, i.e., involves force between 2 masses. However, I've runinto what maybe (or maybe not) a problem. Can you point me to where I can get help? The problem is that when I press the x-t-theta-n key, the toolbox solver displays 'a'.

[@scottcollins7513]

It seems that the issue is that the key you are describing assumes you want to continue using the variable that you used most recently in the past. In the solver put in an equation like 3X, using the Alpha key to enter the X - after doing that, on mine the key you are describing changes to enter an X rather than an A or whatever previous variable you had been using. The other thing you can do is switch to a different app like finance if you’re having a problem with the key you were describing when you are in the normal home screen or CAS screen.

[@mizusada5274]

Why r is not square on denominator in E8 formula?

[@scottcollins7513]

Good catch. I messed up when I made the video.

[@wesleydevries7415]

Hey Scott, I'm an aerospace engineer, doing my masters' and I am wondering whether you would recommend the HP Prime over a Casio Casio FX-CG50. Could you give me your opinion please?

[@scottcollins7513]

Wesley, I'm not sure what to tell you. I got a BSME back before the internet, so I'm not sure I am the guy to recommend anything. Also, I'm not familiar at all w/ the Casio fx-CG50. I will say that I find the hp Prime underwhelming in terms of the way it handles vectors -- esp 3D. In my mind, aerospace engineering is going to involve a lot of 3D vectors. You might consider something that handles those in a better-integrated fashion than the hp Prime. My hp 48GX is much better at 3D vectors. I'm not sure what the hp 50 sells for these days, but might be worth at least doing some research on it. Sorry I am not more help here. I think you should talk to your classmates and see what they are using. You might find out that everything is being done using a computer when it is not done by hand. If you have a chance, it would be helpful to hear what you end up going with.

[@wesleydevries7415]

@@scottcollins7513 Thank you for your reply. Could you elaborate on what you mean with handling vectors - esp 3D, please? Do you mean 3D operations, e.g. multiplication, or how they are plotted, etc? I used to have the TI, but that was slow and I really disliked the fact that it did not have a native "fraction" key. The HP prime doesn't have such a button either, but when pressing the quotient key, it automatically allows to enter both sides of the fraction, reducing the need for such a button. Overall the Casio CG50 is easier to work with, but the HP Prime has an edge with the help function which is great.

[@scottcollins7513]

@@wesleydevries7415 Two examples of the Prime's limitations w/ vectors: (1) If you have a rectangular vector and want to quickly convert it to polar (or vice versa), it requires the use of a command that is buried in a menu. Granted, w/ 2D you can use complex numbers as an analog and those are more versatile. Here is a video that touches on this: kzbin.info/www/bejne/pZmVq6yPmc6Ebrs (2) If you want to convert between rectangular (x,y,z) and spherical, I do not think the Prime has any commands to do this. You can create a program to do it, but it's not native. On the hp 48/49/50 this sort of thing is well-integrated. Take all of this w/ a grain of salt, because I am definitely NOT a Prime expert. I will say it just feels less engineering-geared when compared w/ the classic hp 48/49/50 calculators. Just my (potentially outdated) opinion.

[@wesleydevries7415]

@@scottcollins7513 Thanks for your opinion Scott. I must tell you that I usually calculate those vectors myself, so that's not an issue for me. However, I plan on going through the full instruction manual soon.

[@lol-q1v]

1:58 Error XOXO

[@noahgrayhek1100]

It may be because of how it is saving the variables either as a global variable or a local variable.

[@scottcollins7513]

Sure would be nice if they built a "dynamic variable creation" feature into the solver.

[@noahgrayhek1100]

@@scottcollins7513 my quick fix to this issue (may not be the best but works for me) is I created a variables program where I globally declared all of my variables and that seems to keep them around. I was having similar trouble while writing a mass transfer program and that seemed to fix my problem. It appeared that once the calculator refreshed, it would erase everything except for the variables declared outside of the running program.

[@ErIcSaMpAiO36261000]

@@noahgrayhek1100 I'm having problems using variables from different Export Eg: EXPORT a,e,i,o,u; EXPORT b,c,d. I can make X=a*b, but I can't use X=a*e. Can you help me?

[@avolone]

Has to be r^2

[@scottcollins7513]

Correct. I messed up.

[@fernandoj.sulsonaanziani6195]

That's just the stupidity of the modernness of the hp Prime. The HP 50g does NOT have that problem.