Implicit differentiation

[peterkirby]

I'm new to mathcad. Can someone please explain to mein detail the steps needed for mathcad15 to carry out implicit differentiation. The specic example I'm looking at is xy+y^3 = sec(y^2). Thanks in advance. Pete.

[AlvaroDíaz]

If you are learn about implicit differentiation, your example isn't the better to an introductory notes. In the attached you can found the explicit derivative of the function implicitly defined by your relationship.

Regards. Alvaro.

[AlvaroDíaz]

Symbolic solution for the implicit derivative added.

Regards. Alvaro.

[peterkirby]

Alvaro, many thanks for taking the time to help me. I think I'm able to follow the symbolic solution except for the right hand side of the line starting "eq(x,y,y'):=. It has a symbol I don't recognize, followed by a left-pointing arrow. Can you please tell me the key strokes needed for the right hand side of this expression, then I think I will be ok! Again, many thanks. Peter.

[AlvaroDíaz]

The left arrow is for symbolic evaluations, inserted with Ctrl+period, can learn about it in quicksheets under "Symbolic Math". This strange symbol in eq(x,y,y') is the ascii Alt+232 and it is only to remember me that the assignation was delayed -can susbtitute it by a letter, like A-, and usually I do this only for break the line. Itis less efficient than the usual way to assign in the same line: so, don't pay attention to it, can do the assignation and the evaluation in the same line, as it is usual.

Regards. Alvaro.

[RichardJ]

The left arrow is for symbolic evaluations

I think a couple of your synapses just misfired

Left arrow is local assignment.

[AlvaroDíaz]

Bah, that's nothing. Do you imagine me driven at UK? Well, if you don't, please, remains doing not it. Do you think that this mistake represent an agravant when the judge want enjanil me? ( - :

Thanks. Alvaro.

[peterkirby]

Hi Alvaro. Just a couple more questions. How do I insert the "substitute, dy(x)/dx=y' and substitute, y(x)=y' ( I know that the prime is inserted by keying Ctrl F7, and that the vertical line is obtained from "add line" in the programming toolbar). Also, How do I obtain the command "Given"? I'm almost there and I much appreciate your help (and patience!). Regards, Peter.

[AlvaroDíaz · Accepted solution]

Nope. Here is your problem: isn't the same vertical bar which is in the programming toolbar than the used for symbolic combination of more than one symbolic statmen

t. To add more than one symbolic command you mus to type Ctrl + Shift + period. In the image, this was done four times

For the Given command I feel that you can learn about it in the quick sheets; they are much better than the usual help. Check the worksheet "

Solving Nonlinear Systems of Equations" under "Solver Equations".

Regards. Alvaro

[Justin]

How did you prevent mathcad from evaluating symbolically in the first part of your symbolic solution?

[VladimirN]

Right click on the math region and choose "Disable Evalution":

[RichardJ]

It's because of the local assignment operator (the left pointing arrow, from the programming toolbar)