We can restore the interpolation functions: lspline(), pspline() and cspline(). This is how the cspline() function works. Based on the attached document and file from the PTC Mathcad forum.



Cubic spline interpolation using Mathcad (2009).pdf (257kb) downloaded 40 time(s).
cspline1.mcdx.zip (13kb) downloaded 13 time(s).

cspline.sm (39kb) downloaded 22 time(s).
cspline.pdf (89kb) downloaded 16 time(s).

Edited by user 10 December 2021 13:42:42(UTC)  | Reason: Not specified

rkfixed(3|4) added, but I still don’t know which derivative symbol is better to take. (ʹ) - modifier letter prime (U+02B9) used below. I don't know how to enter it from the keyboard.

Edited by user 10 December 2021 13:43:39(UTC)  | Reason: Not specified

This can be done in 2 steps:

1. Copy \02B9\ to text region. This code will turn into a text simbol (ʹ).
2. Select and copy it as variable name.

PS. It looks like it's time to combine all Mathcad functions into one plugin - Mathcad Toolbox. It will contain all such functions: ODE solvers, spline functions, in/out functions and so on.

Edited by user 05 December 2021 16:29:09(UTC)  | Reason: Not specified

This looks very interesting. Seems that it is not yet in the online gallery?

In principle, the built-in diff(1) operator would be an option but it looks ugly if applied twice.
The ordinary prime would be ok for me (just as it is used as tag in unit names), it is input as Shift # on german keyboards.


diff2.sm (3kb) downloaded 11 time(s).

I can't contact Andrey directly. The server does not allow compiling the sources, as there is no free space. Therefore, the latest changes are not yet available.

I've made some changes. I liked the idea with the str2num() function. Also I can override the diff(1) function, but that can be confusing.

Now it is possible to numerically solve the Cauchy problem for one variable: diff(y(x),x,n)=F(x,y(x),...,diff(y(x),x,n-1)) . Later, I will expand the rest of the ODE solvers to support this simplified form. But for this I need to combine plugins and add interpolation functions similar to Mathcad (lspline(), interp(), ...). It will be more convenient for me to test the solvers, comparing the results with Mathcad.

Block region collects equations in the form of a system and substitutes it as the first parameter into the function.

Edited by user 10 December 2021 13:45:12(UTC)  | Reason: Not specified

Plugin updated. Please try.

Examples:



Changes:

- rkfixed() now works correctly;
- Odesolve block renamed to Mathcad Block;
- the task for the ODE solver in the usual mathematical notation is supported;
- default diff symbol is apostrophe ( ' );
- linterp() is used as an interpolation function;
- refactored.

Edited by user 10 December 2021 13:43:52(UTC)  | Reason: Not specified

I will add the interpolation functions ( interp(), lspline(),... ) to the plugin and rename it to Mathcad Toolbox. After that, it will be possible to test its work, comparing it with the Mathcad numerically.

Edited by user 06 December 2021 21:46:41(UTC)  | Reason: Not specified

Really nice generic block concept! It is a really good reason for updating the handbook and the portable distribution.

This is how to use it with symbolic solutions using Solve() (Maxima plugin):


Solve block.sm (6kb) downloaded 26 time(s).

Looking forward to a RK integrator for multi-DOF systems. This is how I would imagine the user interface.


Federpendel-block.sm (49kb) downloaded 28 time(s).

Plugin updated.

Changes:

- plugin merged with Mathcad File Access (all functions are inside Mathcad Toolbox);
- the condition has changed in the definition of the solver function (to support both directions of integration): (x-xmin)*(xmax-x)>=0;
- pspline() function added.

Looks great, but something is missing.

Edited by user 10 December 2021 13:44:39(UTC)  | Reason: Not specified