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Anyone know of graphing software on the computer that can graph arbitrary inequalities and logical expressions like the HP Prime's advanced graphing can? [0] Fo

Anyone know of graphing software on the computer that can graph arbitrary inequalities and logical expressions like the HP Prime's advanced graphing can? [0] For example, if you say x^2 = y it will draw a sideways parabola, top and bottom (yes, it's not a function). Or if you say 10 = x^2 + y^2 it will draw a circle without any gaps. Or if you say sin((1+sin(x+y))*asin(.5*(sin(x)+sin(y)))+(1+sin(x-y))*asin(.5*(cos(x)+cos(y))))=0 it draws something like a chain link fence. [1] It works well on a battery operated calculator, so a desktop computer should have no trouble with it, but does the software exist? [0]: https://www.youtube.com/watch?v=GAVqjBxFyXA https://www.youtube.com/watch?v=GAVqjBxFyXA [1]: https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fwww.techpoweredmath.com%2Fimg%2Fhp-prime-advanced-graphing.jpg&f=1&nofb=1 https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2F...

maxwelljoslyn 6y ago
On HN a few days ago, I saw a Windows program which seemed like it would do as you describe (and much more.) But - curses - I didn't bookmark it, at least not in the normal place. I'll look a little harder for you. If I don't update/follow up on this comment, assume I didn't find it. :( EDIT: Aha. It's called "EvalDraw." Cheers to user 'TeMPOral for sharing. https://news.ycombinator.com/item?id=25575775 https://news.ycombinator.com/item?id=25575775
- TeMPOraL 6y ago
  Yup, I usually used EvalDraw in (x,y) mode to graph inequalities. You have to remember though that equations like x=y or x-y = 0 represent a line - an infinitely thin object - so EvalDraw will likely not draw you anything given such input. You have to translate your equation into something that has thickness. E.g. an f(x) = 0 into abs(f(x)) < 0.01 For instance, GP's example: (x,y) abs(sin((1+sin(x+y))asin(.5(sin(x)+sin(y)))+(1+sin(x-y))asin(.5(cos(x)+cos(y)))))<0.01 Draws a beautiful red chain-link fence on blue background. If you can rewrite your formula to give you a value between 0 and 1, you'll get a nice color gradient. And then you can have more direct control over colors using some of the things I described in the linked comment.
mojomark 6y ago
Have you tried the Wolfram Alpha app? I didn't try all of the examples you posted, but graphing a circle works fine. I use this app all the time to help me simplify expressions (I'm an engineer - I use math, I love math, but I am no mathematician, so I seek shortcuts where I can to save time). 1.) Compute '10 = x^2 + y^2' with the Wolfram|Alpha website (https://www.wolframalpha.com/input/?i=10+%3D+x%5E2+%2B+y%5E2 https://www.wolframalpha.com/input/?i=10+%3D+x%5E2+%2B+y%5E2) or mobile app (wolframalpha:///?i=10+%3D+x%5E2+%2B+y%5E2).
- Buttons840 6y ago
  I was hoping to be able to utilize the incredible calculator I possess, but it's a good suggestion even if it's not what I'm hoping for.
bbkane 6y ago
Maybe Sage? See http://utmost-sage-cell.org/sage:implicit-functions-plot http://utmost-sage-cell.org/sage:implicit-functions-plot
interpol_p 6y ago
If you have a mac the built in Grapher.app (in Applications/Utilities) can graph those things. I pasted your chain-link-fence example and it graphs fine
lifthrasiir 6y ago
GrafEq [1] from Pedagoguery Software is one of best-known softwares that can handle a variety of implicit 2D plots (it's a shareware, though). The algorithm for its earlier version is based on generalized interval arithmetics and described in the author's thesis [2]. I like it so much that reimplementing it is one of my (ever-growing) longer-term projects... [1] http://www.peda.com/grafeq/ http://www.peda.com/grafeq/ [2] http://www.dgp.toronto.edu/~mooncake/thesis.pdf http://www.dgp.toronto.edu/~mooncake/thesis.pdf
dllu 6y ago
I made an implicit plotter here: https://daniel.lawrence.lu/blog/y2016m02d08/ https://daniel.lawrence.lu/blog/y2016m02d08/ Your function works fine here and my blog post contains many examples of other cool functions to plot, including the pathological exp(sin(x) + cos(y)) - sin(exp(x+y)) = 0 My plotter is very slow, however; it uses random sampling instead of any sort of clever interval arithmetic.
Foobar8568 6y ago
HP Prime and some other calculators (at least one TI) is based on GIAC XCas so here you go https://www-fourier.ujf-grenoble.fr/~parisse/giac.html https://www-fourier.ujf-grenoble.fr/~parisse/giac.html
mkl 6y ago
Desmos and GeoGebra can both do this (though GeoGebra has little gaps in this particular example, and you'll need arcsin rather than asin for both tools). If you want programming-oriented, Sympy can do an okay job (asin), as can Numpy (arcsin), but the latter involves more mucking about, evaluating on a grid.
ttoinou 6y ago
MathStudio on iOS is really good for that purpose http://mathstud.io/apps/ http://mathstud.io/apps/ I thought it was called SpaceTime before, not sure

maxwelljoslyn 6y ago

On HN a few days ago, I saw a Windows program which seemed like it would do as you describe (and much more.) But - curses - I didn't bookmark it, at least not in the normal place. I'll look a little harder for you. If I don't update/follow up on this comment, assume I didn't find it. :( EDIT: Aha. It's called "EvalDraw." Cheers to user 'TeMPOral for sharing. https://news.ycombinator.com/item?id=25575775 https://news.ycombinator.com/item?id=25575775

TeMPOraL 6y ago
Yup, I usually used EvalDraw in (x,y) mode to graph inequalities. You have to remember though that equations like x=y or x-y = 0 represent a line - an infinitely thin object - so EvalDraw will likely not draw you anything given such input. You have to translate your equation into something that has thickness. E.g. an f(x) = 0 into abs(f(x)) < 0.01 For instance, GP's example: (x,y) abs(sin((1+sin(x+y))asin(.5(sin(x)+sin(y)))+(1+sin(x-y))asin(.5(cos(x)+cos(y)))))<0.01 Draws a beautiful red chain-link fence on blue background. If you can rewrite your formula to give you a value between 0 and 1, you'll get a nice color gradient. And then you can have more direct control over colors using some of the things I described in the linked comment.

mojomark 6y ago

Have you tried the Wolfram Alpha app? I didn't try all of the examples you posted, but graphing a circle works fine. I use this app all the time to help me simplify expressions (I'm an engineer - I use math, I love math, but I am no mathematician, so I seek shortcuts where I can to save time). 1.) Compute '10 = x^2 + y^2' with the Wolfram|Alpha website (https://www.wolframalpha.com/input/?i=10+%3D+x%5E2+%2B+y%5E2 https://www.wolframalpha.com/input/?i=10+%3D+x%5E2+%2B+y%5E2) or mobile app (wolframalpha:///?i=10+%3D+x%5E2+%2B+y%5E2).

Buttons840 6y ago
I was hoping to be able to utilize the incredible calculator I possess, but it's a good suggestion even if it's not what I'm hoping for.

bbkane 6y ago

Maybe Sage? See http://utmost-sage-cell.org/sage:implicit-functions-plot http://utmost-sage-cell.org/sage:implicit-functions-plot

interpol_p 6y ago

If you have a mac the built in Grapher.app (in Applications/Utilities) can graph those things. I pasted your chain-link-fence example and it graphs fine

lifthrasiir 6y ago

GrafEq [1] from Pedagoguery Software is one of best-known softwares that can handle a variety of implicit 2D plots (it's a shareware, though). The algorithm for its earlier version is based on generalized interval arithmetics and described in the author's thesis [2]. I like it so much that reimplementing it is one of my (ever-growing) longer-term projects... [1] http://www.peda.com/grafeq/ http://www.peda.com/grafeq/ [2] http://www.dgp.toronto.edu/~mooncake/thesis.pdf http://www.dgp.toronto.edu/~mooncake/thesis.pdf

dllu 6y ago

I made an implicit plotter here: https://daniel.lawrence.lu/blog/y2016m02d08/ https://daniel.lawrence.lu/blog/y2016m02d08/ Your function works fine here and my blog post contains many examples of other cool functions to plot, including the pathological exp(sin(x) + cos(y)) - sin(exp(x+y)) = 0 My plotter is very slow, however; it uses random sampling instead of any sort of clever interval arithmetic.

Foobar8568 6y ago

HP Prime and some other calculators (at least one TI) is based on GIAC XCas so here you go https://www-fourier.ujf-grenoble.fr/~parisse/giac.html https://www-fourier.ujf-grenoble.fr/~parisse/giac.html

mkl 6y ago

Desmos and GeoGebra can both do this (though GeoGebra has little gaps in this particular example, and you'll need arcsin rather than asin for both tools). If you want programming-oriented, Sympy can do an okay job (asin), as can Numpy (arcsin), but the latter involves more mucking about, evaluating on a grid.

ttoinou 6y ago

MathStudio on iOS is really good for that purpose http://mathstud.io/apps/ http://mathstud.io/apps/ I thought it was called SpaceTime before, not sure