topic Re: M14 2D Plot bug? in PTC Mathcad
https://community.ptc.com/t5/PTC-Mathcad/M14-2D-Plot-bug/m-p/272735#M106570
<HTML><HEAD></HEAD><BODY><BLOCKQUOTE><TABLE border="1"><TBODY><TR><TD><P> If it is not a bug then am I doing something wrong with my logic tests</P></TD></TR></TBODY></TABLE></BLOCKQUOTE><P>no</P><BLOCKQUOTE><TABLE border="1"><TBODY><TR><TD><P> or the way I create the functions to be plotted? </P></TD></TR></TBODY></TABLE></BLOCKQUOTE><P>no again.</P><P></P><P>The reason you encounter those strange effects is because you use Mathcads quickplot feature. Normally to plot a function like sin(x) you write sin(x) at the ordinate and x at the abscissa and x is not defined in the sheet. Mathcad choses a range (-10 to 10 unless you specify other by the limit placeholders), divides that range in 1000 (? not sure about that, at least a fix number) intervals calculates the function values and plots. Mathcads works on the value on the abscissa and this works pretty well as long as the independent variable is placed at the abscissa. switching axis is calling for troubles and thats exactly what you have done. Your independent variable ia´s placed at the vertical ordinate and the dependent function at the abscissa. This tends to make Mathcads quickplot feature fail sometimes.</P><P></P><P>Way out is to</P><UL><LI>plot one precalculated vector of ordinate values over another vector of y-values</LI><LI>create a vector of y-values and a corresponding rrange variable i, put y[i at the ordinate and on the abscissa evaluate your functions for the individual vector elements y[i. Thats what Alan has suggested.</LI><LI>make the undefined y a range varible with the desired step width. See attached sheet. I have chosen the values for y.start and y.end from your first plot. I hope its the same range for all the plots (I haven't checked it but the plots look OK for me) otherwise you would have to redefine y befor the plot with different ranges. That way it would not be necesary to specify the end values for y in the plot (thats also true for Alans way).</LI></UL><P></P><P>BTW, its a good idea to use ranges or vector in plots even if the quickplot feature works as it gives you more and more convenient control over the range end values and the precision/number of points to be plotted.</P></BODY></HTML>Tue, 18 Mar 2014 20:17:16 GMTWerner_E2014-03-18T20:17:16ZM14 2D Plot bug?
https://community.ptc.com/t5/PTC-Mathcad/M14-2D-Plot-bug/m-p/272732#M106567
Hello,I am having an issue with 2D plots in mathcad. I am unsure if there is a bug, or I am not understanding something. I am using M14 M020 14.0.2.5.The main issue is that when using certain values for variables, my 2D plots will no longer display. See attached worksheet. With theThu, 03 May 2018 16:24:02 GMThttps://community.ptc.com/t5/PTC-Mathcad/M14-2D-Plot-bug/m-p/272732#M106567DB072018-05-03T16:24:02ZRe: M14 2D Plot bug?
https://community.ptc.com/t5/PTC-Mathcad/M14-2D-Plot-bug/m-p/272733#M106568
<HTML><HEAD></HEAD><BODY><P>Safest to define individual values of y first, then call the sigmas etc. with the individual values, otherwise some of the logic tests get confused. See attached.</P><P></P><P>Nothing to do with a bug.</P><P></P><P>Alan</P></BODY></HTML>Tue, 18 Mar 2014 14:49:27 GMThttps://community.ptc.com/t5/PTC-Mathcad/M14-2D-Plot-bug/m-p/272733#M106568AlanStevens2014-03-18T14:49:27ZRe: M14 2D Plot bug?
https://community.ptc.com/t5/PTC-Mathcad/M14-2D-Plot-bug/m-p/272734#M106569
<HTML><HEAD></HEAD><BODY><P>That works great, thanks for the help Alan. Although I'm still not sure I understand why that was happening. </P><P></P><P> If it is not a bug then am I doing something wrong with my logic tests, or the way I create the functions to be plotted? I'm still in the debugging stage, and so far the results seem to be correct but I haven't run through all possible scenarios yet so I don't know if the actual sigma values are being affected by a mistake in the logic, or if it was just an issue with the plots.</P></BODY></HTML>Tue, 18 Mar 2014 16:26:21 GMThttps://community.ptc.com/t5/PTC-Mathcad/M14-2D-Plot-bug/m-p/272734#M106569DB072014-03-18T16:26:21ZRe: M14 2D Plot bug?
https://community.ptc.com/t5/PTC-Mathcad/M14-2D-Plot-bug/m-p/272735#M106570
<HTML><HEAD></HEAD><BODY><BLOCKQUOTE><TABLE border="1"><TBODY><TR><TD><P> If it is not a bug then am I doing something wrong with my logic tests</P></TD></TR></TBODY></TABLE></BLOCKQUOTE><P>no</P><BLOCKQUOTE><TABLE border="1"><TBODY><TR><TD><P> or the way I create the functions to be plotted? </P></TD></TR></TBODY></TABLE></BLOCKQUOTE><P>no again.</P><P></P><P>The reason you encounter those strange effects is because you use Mathcads quickplot feature. Normally to plot a function like sin(x) you write sin(x) at the ordinate and x at the abscissa and x is not defined in the sheet. Mathcad choses a range (-10 to 10 unless you specify other by the limit placeholders), divides that range in 1000 (? not sure about that, at least a fix number) intervals calculates the function values and plots. Mathcads works on the value on the abscissa and this works pretty well as long as the independent variable is placed at the abscissa. switching axis is calling for troubles and thats exactly what you have done. Your independent variable ia´s placed at the vertical ordinate and the dependent function at the abscissa. This tends to make Mathcads quickplot feature fail sometimes.</P><P></P><P>Way out is to</P><UL><LI>plot one precalculated vector of ordinate values over another vector of y-values</LI><LI>create a vector of y-values and a corresponding rrange variable i, put y[i at the ordinate and on the abscissa evaluate your functions for the individual vector elements y[i. Thats what Alan has suggested.</LI><LI>make the undefined y a range varible with the desired step width. See attached sheet. I have chosen the values for y.start and y.end from your first plot. I hope its the same range for all the plots (I haven't checked it but the plots look OK for me) otherwise you would have to redefine y befor the plot with different ranges. That way it would not be necesary to specify the end values for y in the plot (thats also true for Alans way).</LI></UL><P></P><P>BTW, its a good idea to use ranges or vector in plots even if the quickplot feature works as it gives you more and more convenient control over the range end values and the precision/number of points to be plotted.</P></BODY></HTML>Tue, 18 Mar 2014 20:17:16 GMThttps://community.ptc.com/t5/PTC-Mathcad/M14-2D-Plot-bug/m-p/272735#M106570Werner_E2014-03-18T20:17:16ZRe: M14 2D Plot bug?
https://community.ptc.com/t5/PTC-Mathcad/M14-2D-Plot-bug/m-p/272736#M106571
<HTML><HEAD></HEAD><BODY><P>Thank you for that clear explanation Werner Exinger! Your post helped me understand the consequences of flipping the x and y axis in the plot. I should have known it wouldn't be as simple as I had hoped! </P><P></P><P>Kudos to both of you for your knowledge and taking the time to help out a mathcad newbie.</P></BODY></HTML>Wed, 19 Mar 2014 12:12:01 GMThttps://community.ptc.com/t5/PTC-Mathcad/M14-2D-Plot-bug/m-p/272736#M106571DB072014-03-19T12:12:01Z