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ptc-17390381-Visitor
1-Visitor
January 18, 2020
Question

problem solving equations with Prime 6

  • January 18, 2020
  • 3 replies
  • 2853 views

At the moment my students work with sin, cos , tan. As simple equation the should calculate the intervall where  5sin(x) is at least 3.

In Prime 5 one gets the (first) 2 solutions at once: prime5.png

But in Prime 6 there is only one solution:  prime6.png

To get the 2. solution one has to use the "solver block" which makes things complicated.

Why is it that P6 can solve fewer equations than 5 and sometimes gives fewer solution and I cannot find a way to get all the solutions with solve?? Bug or Feature ??? I figured that "new calculation engine" means better calculation engine ....

3 replies

P
ptc-17390381-VisitorAuthor
1-Visitor
January 18, 2020

BTW: a good CAS like Mathematica gives all of the solutions ....

mathematica.png

Sadly we cannot use this in our schools (no money ...)

ttokoro
ttokoro21-Topaz I
21-Topaz I
January 18, 2020

Use legacy symbolic engine.

t.t.
    L
    LucMeekes23-Emerald IV
    23-Emerald IV
    January 18, 2020
    Every improvement is, or involves, a change. But the reverse is not true!
    Prime is newer than (real) Mathcad, but it is not better on all aspects....
    Fortunately for your case there is a way out. Prime 6 allows to choose the old symbolic engine, the one that served all previous versions of Prime as well as (real) Mathcad 14 en 15.
    Did you try to ask the symbolic solver for 'all' solutions? ( "solve, x, all") ?

    Success!
    Luc
      P
      ptc-17390381-VisitorAuthor
      1-Visitor
      January 18, 2020

      using the all option in 6 gives 2 solutions, but the second one given is 0 which mathematically is total b*s* or I don't understand the meaning of [0.6435 0] .....

      switching back to legacy engine works - but this cannot be a solution ....

      Thanks anyway

      W
      Werner_E25-Diamond I
      25-Diamond I
      January 18, 2020
      @ptc-1739038 wrote:

      using the all option in 6 gives 2 solutions, but the second one given is 0 which mathematically is total b*s* or I don't understand the meaning of [0.6435 0] .....

      I think Luc meant "fully" instead of "all".

       

      switching back to legacy engine works - but this cannot be a solution ....

      If you want to see the correct results its the only solution apart from switching over to a different software.

       

      It looks like PTC never had improvement of quality in mind when they developed Prime and the same is the case when it comes to change the symbolic engine.

      The legacy engine (muPad) had to be licensed from Mathworks (the makers of Matlab) and PTC sure did not like the idea to have to license technology from a competitor. Maybe Mathworks doesn't even want to renew their deal with PTC, who knows?

      In this forum there were already reported quite some problems with the new symbolic engine but I don't have much hope that PTC will address and fix them.

       

      Below you can see the result of the "fully" modifier. As you can see even the new engine gives you all results but in a weird and (for your purpose possibly) unusable way. The new engine also ignores the "assume" modifier.

      While we can talk the old engine into displaying the result in a similar way as the new one using the "rewrite" modifier, it unfortunately does not work the other way round - the new engine will not display the result using the "asin" function.

       

      So the conclusion is that the change of the symbolic engine is just another step of PTCs consequent attempts to destroy the Mathcad we knew.

      Werner_E_0-1579347020548.png

       

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