# User Portlet

Discussions |
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After days of frustration, I have written a way to automate localization of variables declared inside the code, however due to quirks of the Wolfram language it appears I cannot make it into a function. Thank you though. |

So, I'm attempting to emulate MatLab functions in Mathematica (mainly for practice in programming) and I have run across a very peculiar error where If doesn't simplify down to the False portion of the function: Trapz[xlist_: Null, ylist_] :=... |

Thank you for your response Neil, however this isn't what I'm looking for. I'm in need of something that will either look for trueness in the left hand side of the *> or a structure match and then evaluate the right hand side of the *> that way I can... |

I misread your statement, never mind the above post. |

The differential equation `y'[t]^2+y''[t]==0` with initial conditions `y'[1] ==1` and `y[1] == 0` contains a pole at `t = 0` however, is there a way to find out that a given differential equation with provided initial conditions has poles and what... |

There appears to be a problem with this approach. If my simple understanding of matrices is correct, you cannot invert a matrix if there is a matrix inside of it because the inverse of a matrix and the original matrix multiply (A A^-1 or A^-1 A) to... |

The following .nb file is simply Newton's equation for gravity after being integrated to obtain a related differential equation. To obtain the new equation, one simply takes: y" = k/y^2 Multiply by y' then integrate from 0 to t: y'[t]^2/2-y'[0]^2/2... |

Ahh, my mistake was so simple, I should slap myself. Thank you, I spent a few hours looking over this thing trying to figure out my error just to simply find out (because of the .nb file that was provided) that instead of putting `{X[t], Y[t]}` I was... |

It's a start, but more like when I hover over the bracket, it will highlight everything between that bracket and its respective end bracket. Not necessarily select it though. |

Okay, thank you Daniel. I've known that this works, but thought that implementation of an automated "limit approacher" would be something that Mathematica users might find useful for such occasions. |