topic Re: Sometimes when I evaluate a derivative symbolically in mathcad of a certain function, it gives me 0 when its not in Mathcad https://www.ptcusercommunity.com/t5/Mathcad/Sometimes-when-I-evaluate-a-derivative-symbolically-in-mathcad/m-p/163180#M63937 <HTML><HEAD></HEAD><BODY><P>It's a problem with labels. You have two occurrences of phi with different labels, so Mathcad views them as different. It's equivalent to d/dA(f(B)), which is of course zero. Set the labels to both be "variable" and it works</P><P><IMG __jive_id="89955" alt="" class="jive-image image-1" src="https://community.ptc.com/legacyfs/online/89955_pastedImage_3.png" style="max-width: 1200px; max-height: 900px;" /></P><P></P><P>In Mathcad Prime you have to be careful with labels!</P><P></P><P>It would have been better to continue the previous thread rather than starting a new one.</P></BODY></HTML> Tue, 21 Jul 2015 22:56:38 GMT RichardJ 2015-07-21T22:56:38Z Sometimes when I evaluate a derivative symbolically in mathcad of a certain function, it gives me 0 when its not https://www.ptcusercommunity.com/t5/Mathcad/Sometimes-when-I-evaluate-a-derivative-symbolically-in-mathcad/m-p/163178#M63935 Sometimes when I evaluate a derivative symbolically in mathcad of a certain function, it gives me 0 when its not. can anyone help? Thu, 03 May 2018 15:16:09 GMT https://www.ptcusercommunity.com/t5/Mathcad/Sometimes-when-I-evaluate-a-derivative-symbolically-in-mathcad/m-p/163178#M63935 prajendran 2018-05-03T15:16:09Z Re: Sometimes when I evaluate a derivative symbolically in mathcad of a certain function, it gives me 0 when its not https://www.ptcusercommunity.com/t5/Mathcad/Sometimes-when-I-evaluate-a-derivative-symbolically-in-mathcad/m-p/163179#M63936 <HTML><HEAD></HEAD><BODY><P>Separate out the function, and it will evaluate.&nbsp; Don't know why your sheet fails.</P></BODY></HTML> Tue, 21 Jul 2015 19:41:53 GMT https://www.ptcusercommunity.com/t5/Mathcad/Sometimes-when-I-evaluate-a-derivative-symbolically-in-mathcad/m-p/163179#M63936 Fred_Kohlhepp 2015-07-21T19:41:53Z Re: Sometimes when I evaluate a derivative symbolically in mathcad of a certain function, it gives me 0 when its not https://www.ptcusercommunity.com/t5/Mathcad/Sometimes-when-I-evaluate-a-derivative-symbolically-in-mathcad/m-p/163180#M63937 <HTML><HEAD></HEAD><BODY><P>It's a problem with labels. You have two occurrences of phi with different labels, so Mathcad views them as different. It's equivalent to d/dA(f(B)), which is of course zero. Set the labels to both be "variable" and it works</P><P><IMG __jive_id="89955" alt="" class="jive-image image-1" src="https://community.ptc.com/legacyfs/online/89955_pastedImage_3.png" style="max-width: 1200px; max-height: 900px;" /></P><P></P><P>In Mathcad Prime you have to be careful with labels!</P><P></P><P>It would have been better to continue the previous thread rather than starting a new one.</P></BODY></HTML> Tue, 21 Jul 2015 22:56:38 GMT https://www.ptcusercommunity.com/t5/Mathcad/Sometimes-when-I-evaluate-a-derivative-symbolically-in-mathcad/m-p/163180#M63937 RichardJ 2015-07-21T22:56:38Z Re: Sometimes when I evaluate a derivative symbolically in mathcad of a certain function, it gives me 0 when its not https://www.ptcusercommunity.com/t5/Mathcad/Sometimes-when-I-evaluate-a-derivative-symbolically-in-mathcad/m-p/163181#M63938 <HTML><HEAD></HEAD><BODY><P>I couldn't attach a new file in the reply.... so i had 2 start a new one....</P></BODY></HTML> Sat, 25 Jul 2015 19:40:27 GMT https://www.ptcusercommunity.com/t5/Mathcad/Sometimes-when-I-evaluate-a-derivative-symbolically-in-mathcad/m-p/163181#M63938 prajendran 2015-07-25T19:40:27Z Re: Sometimes when I evaluate a derivative symbolically in mathcad of a certain function, it gives me 0 when its not https://www.ptcusercommunity.com/t5/Mathcad/Sometimes-when-I-evaluate-a-derivative-symbolically-in-mathcad/m-p/163182#M63939 <HTML><HEAD></HEAD><BODY><P>I dont know where I had phi as different labels?</P></BODY></HTML> Sat, 25 Jul 2015 19:44:35 GMT https://www.ptcusercommunity.com/t5/Mathcad/Sometimes-when-I-evaluate-a-derivative-symbolically-in-mathcad/m-p/163182#M63939 prajendran 2015-07-25T19:44:35Z