I open this topic for the snippets hatch and fill, as a place for further disussions.

You find these snippets and a corresponding example in the extension manager (online gallery).

Previous discussion can be found here.

Two types of shading

"memory allocation" vs "memory NOT allocation" is confusing to me.
Memory allocales itself from the construction. Visit the "Spot"
"stack" is very fast as being a vector operation. "augment" is slow
as not being a direct vector operation, but very fast within a program.
"hatch" creates a virtual matrix, a scalar matrix, i.e: a matrix at the
plot canvas. Same principle than plotting f(x) on the QuickPlot canvas.
Great construction, though I never used it. Watch it does not face infinity
governed by the N ... at infinity: it crashes Smath !

Jean

Forum Test Derivative.sm (12kb) downloaded 58 time(s).

Utilities Discrete Spot.sm (13kb) downloaded 59 time(s).

It is supossed that second algorithm must to be faster than your's, but it isn't.

Best regards.

Alvaro.

Much faster than what? Please provide an example to discuss.



It's a common practice in libraries to pre-allocate some space for any container. Without this, it would be very inefficient to manage memory. Further, re-allocation strategies on the low level are quite efficient, because they either use % of current size to grow (typical are 2x or golden ratio), or linked lists that don't need reallocation at all. SMath doesn't need to do that itself, because it's .NET that does that for it. And it's VERY efficient for general cases.



Well, your slower second time could be explained like this:
pre-allocation in SMath is high-level operation, and it simply adds one additional high-level (slow) operation.

And it could explain something, if not one little thing ... actually it doesn't matter.
SMath calculation time is very volatile, and it's hard to measure time reliably, even doing multiple comparisons/calculations. E.g., processor temperature, that raises towards second calculation, may cause it to slow down to prevent overheating (contemporary systems do that). Some memory leaks in SMath may cause slow-down of all subsequent calculations (and when the sheet is done calculation, .NET garbage collection may clean it up, so recalculation shows the same picture).

Here is a screenshot that shows that your "second" calculation, put first, outperforms original.

Than I can explain or understand. Sorry, have not examples of that.




Thanks for the explanation, now I understand why mkraska says "The fastest way seems to be direct element adressing without pre-allocation". Because preallocating is with a high level instruction, and then is slow. Even I have the doubt about why NET pre-allocat V:=0 as matrix when user define that as scalar. I suposse that default SMath types are complexes, not matrices.

So, for the best practices book in SMath, which is best? Never preallocat? Or there are some size when NET take more time than SMath because the NET pre-pre-allocation (the jus't in case one) isn't enough big?

Best regards.

Alvaro.

Like this Alvaro in my own words,

Mathcad up to 11 [my last version up to may 30 that PT deactivated all Single User Edition]
Mathcad XY plot is on "pica" [from recollection 8 pixels] thus the imposibility to equally size
two graphs in height/width. Smath plots on the canvas pixel. Each time it reaches a pixel it
calculates the ordinate value and plug the color, thus finally tracing the function. This porocess
is very fast, but at the kernel level and not accessible to user. To get an export trace then you
must create a vector of discrete values in the number of points as you wish.

Martin program is very crafty ! Instead of hatching by creating each vertical bar manually, it
creates the same as manual but adjustabe in 'N' and between the two plots in question. His argument
of the plot is f,g,x.1,x.2,N in hatch(f,g,x.1,x.2,N), just like asking to plot 'x' in ln(x).
So, 'f,g,x.1,x.2,N' is purely "scalar" in the sense of a vanishing iterator once done the plotted
value on the Smath QuickPlot.

As you remember from Mathsoft Collaboratory, so much I loved Mathcad 2D ...
... so much Smath QuickPlot produces more convenient graphs. OK, some missing features but monkeys
survive with bananas only, is it ? On the hatching demo [attached next post], if you plot points
the hatching looks blank. Not at all, they are all there but not joining because the points confuse
on each plot trace.

Jean

... works as expected !



Maths Tangent.sm (19kb) downloaded 71 time(s).

Only the first module works. The ones "if/else" do not in Smath 5346
The first module is fully compatible with Maxima X_Y plot, i.e:
traces color, symbols, hatching color ... great for publishing.
Martin scalar hatching is slightly faster, not to account in project.
Your module [Alvaro] is great for extracting a particular bar but
couldn't add to the plot ???

Tanks, Jean




2DPlots Hatch Demo [Martin, Alvaro].sm (24kb) downloaded 65 time(s).