Hello together,

why does SMath say "x - not defined" to sqrt(x-7)+sqrt(17-x)= ?

I can't even enter the 4 at the end of the expression.

Is there a small tutorial for pupils? Some curve discussion for example.

Regards from Germany

Sascha

Thank you.

There is a problem with different Regional Settings. If you have Russian Regional settings you will have to use
-comma "," for the decimal separator (Although in the Arithmetic palete the tooltip will say "Decimal point" )
-semicolumn ";" for the argument separator
For instance
res←solve(x-20≡5;x)
res=25
solve(x*20≡5;x)—1/4
solve(x*20≡5;x)=0,25

If you use the English Reginal settings you will have to use
-point "." for the decimal separator
-comma "," for the argument separator
(Can not be displayed here with "MATH" BBcode tag)
Please take a look at the Arithmetic palete or your Reginal Settings. I do not know what yoy did, actually?

By the way, both Reginal settings will solve your simple equation for me in Smath v0.8, but if I want to upload the file with these equation into "Live" SMath mode I've got the same error as you do: "No real roots" but only for the first (simple) equation. The other two "solve" will give the correct result ???

I've been told by the SMath author that some problems are to be resolved with this Settings and the "Live" mode.
Here are the pictures:
Russian and similar settings

English and similar settings

"Live" mode on this site

Regards,
Radovan

Edited by user 03 July 2009 00:50:50(UTC)  | Reason: Not specified

Have you checked the Roots(range) option?
For instance, this will work

but this will not (25 is outside the range[-20,20])


By the way, Roots(range) might effect on the results, especially when there are more than one result.
It might be a problem where searching the roots of different equations. I suppose this would be changed in the next SMath version. On the other hand, it seems that solve is not a symbolical but only a numerical solver at the moment.

Regards,
Radovan

Hello.

It's absolutely true. Solve function includes a simple iteration mechanism.


No. Iteration algorithm has hardcoded step (with ratio to the range - this means that number of steps - constant), that's why answer will be more accuracy if the range will be smaller. And if range will be tot big, then step can be just too big and it can simply jump across the roots.

Edited by user 04 July 2009 01:35:33(UTC)  | Reason: Not specified

omorr, thank you for your posts. They has many useful information for the SMath Studio users.

Good idea! Will be implemented in the release then (in couple of days).

Thank you Andrey

As we know, the problematic equations for root finding could be the equations with small slope at the solutions. Here is a simple example.

SMath solved that quite good (look at the error - order of magnitude 1e-17). But, the inconvenience could be if we try to locate the roots by plotting. I am not sure, but the scaling of the 2D plot could not be done separately on x and y axis. I think we can not locate the rots because of simultaneous scaling of both x and y axis. I spent some time trying (moving and scaling) to locate either one of the roots, but with no success. I do not know if I am right?

Regards,
Radovan

Thank you Andrey for your efforts,

I supose that Roots(range) from the Options menu will be used with solve when the third and fourth argument (range) is not present. Very good, thank you.

I must be annoying but here are few of my findings. I do not think these are critical errors, but just to be for your attention.
Please look at the image:

I did the same as last time - moved the regions up. I expected to se empty placeholder at the numerical evaluation of the matrix inverse?

This one I've already mentioned on the Private Massage. I hope I made myself understood about it. It might be just confusing and prone to errors.

(I did see that I mixed ";" and "," as argument separators - it is Ok, just a typo in the text)
I am on my vacation from tomorow and I will not bother you for about two weeks

Best Wishes,
Radovan

Thank you,

Best wishes to you too

Radovan