I am taking self-faced training to gain Mathcad skills (using Prime 6.0)
In my worksheet, the variable is not accepting. I tries my best without success. So, looking forward to receive help from someone. Thanks a lot.
ACCEPTED SOLUTION
Accepted Solutions
I guess its a combination of two or three things (bugs in Prime).
1) The symbolics doesn't know anything about units
2) Prime very often fails when it comes to autolabelling, especially in conjunction with the symbolics
3) The new symbolics introduced and set by default with Prime 6 is even weaker than the old mupad (which stll can be set via the options.
The main reason is a misinterpretation of the unit psi by the symbolics.
If we evaluate P.seal and G symbolically we see the main problem:
In P.seal psi is correctly recognized as a unit but in G its seen as ordinary variable. So in your second expression using G we actually have psi[unit] and psi[variable] which are treated as two differently variables by the symbolic and they don't cancel.
The new symbolic is too less capable of solving the equation with those two unknowns, the old symbolic (you may give it a try) finds a (huge) solution, which at least gives you the desired result when evaluated numerically:
Fortunately there is a solution built into Prime (which often in such situations does not work as expected but in case of your equation it does).
In the calculation ribbon in calculation option turn on the option "Units/constants in symbolic math" and then recalculate the whole sheet (pressing F5, F9 or Ctrl-F9).
In case you only need the real solution you can use the "assume" modifier as shown in the pic.
I guess its a combination of two or three things (bugs in Prime).
1) The symbolics doesn't know anything about units
2) Prime very often fails when it comes to autolabelling, especially in conjunction with the symbolics
3) The new symbolics introduced and set by default with Prime 6 is even weaker than the old mupad (which stll can be set via the options.
The main reason is a misinterpretation of the unit psi by the symbolics.
If we evaluate P.seal and G symbolically we see the main problem:
In P.seal psi is correctly recognized as a unit but in G its seen as ordinary variable. So in your second expression using G we actually have psi[unit] and psi[variable] which are treated as two differently variables by the symbolic and they don't cancel.
The new symbolic is too less capable of solving the equation with those two unknowns, the old symbolic (you may give it a try) finds a (huge) solution, which at least gives you the desired result when evaluated numerically:
Fortunately there is a solution built into Prime (which often in such situations does not work as expected but in case of your equation it does).
In the calculation ribbon in calculation option turn on the option "Units/constants in symbolic math" and then recalculate the whole sheet (pressing F5, F9 or Ctrl-F9).
In case you only need the real solution you can use the "assume" modifier as shown in the pic.
Two points - one for you and one for those using Mathcad Prime Express.
One: It's often worth doing a check of an expression outside of a definition - it's one of my most useful debugging techniques in Mathcad Prime.
(On a side note, your Figure-2 shows that you're redefining Pseal to take the dimensionless λ values rather than a pressure).
Two: Mathcad Express users don't have the luxury of built-in symbolic processing, but they can still solve some categories of root finding problems, by using the built-in function root.
Stuart
