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J
jlovegrove-21-Visitor
1-Visitor
October 10, 2016
Question

Mathcad Express Prime 3.1 - Handling Equations

  • October 10, 2016
  • 2 replies
  • 4095 views

Many years ago I used MathCad 2.5 and in this one could type in an equation with essentially anything on either side, use a colon as the equal sign and give the equ command.  It did not restrict what you did and there was no attempt to evaluate a variable or expression or assign a value.  On could then go through and modify/manipulate the equation to simplify etc.

Having downloaded the above on a trial basis with a view to buying a licence, I find that this cannot be done,  there seem to be no options other than using = to find the value of a variable or expression or : to assign a value.

Is there any way of just being able to write an equation without either of the above occurring?

2 replies

M
MJG1-Visitor
1-Visitor
October 10, 2016

I think you want the Boolean comparison "equal to".  You can find it under Operators -> Comparison, or you can hold Ctrl and press =.

M
MJG1-Visitor
1-Visitor
October 10, 2016

Also, note that Mathcad can automatically simplify equations or solve for a given variable (no need to manually modify/manipulate).

(examples shown in Mathcad 15, but Prime 3.1 is similar)

F
Fred_Kohlhepp23-Emerald I
23-Emerald I
October 10, 2016

Will Express (aka Free and limited) do that?

L
LucMeekes23-Emerald IV
23-Emerald IV
October 10, 2016

Ah, found what you're referring to. Here's Mathcad 2.50:

It is possible because I set the program to manual, that is, I enforced manual recalculation. In order to calculate I have to press the F9 key. And if I do that, mathcad complains that x is undefined for the equation that starts with 12*x...

You can get a similar effect in Prime if you click the "Stop All Calculations" button in the controls section of the Calculation Tab of the Ribbon.

HOWEVER: Prime will not allow you to enter equations like the second and third shown above, because it maintains that you cannot assign an expression to a calculation; which is a reasonable restriction. Also recent versions of Mathcad (no Prime) will not allow that. I don';t know when this was abandoned, but it may have been thrown out already at version 3 (Mathcad, not Prime).

So if you still want to enter just expressions and to the manipulations yourself, use the boolean equals [CTL-=] to write your equations. And as Mark has shown, recent versions of Mathcad, and also Prime, have the ability to symbolically work such expressions.

I haven't found the "EQU" command in Mathcad 2.50 yet. What would it do?

Success!
Luc

    L
    LucMeekes23-Emerald IV
    23-Emerald IV
    October 10, 2016

    Ah, found it. It's called "eq" and esentially sets to disable evaluation of the expression. It appends a small box at the end of the equation.

    Disable evaluation is still available in modern versions of Mathcad and in Prime it's referred to as "Disable region", but you don't need it if you use the boolean equals symbol to define your equations.

    Luc

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