http://www.mapleprimes.com/questions/141140-Problem-With-Initialboundary-Conditions en-us 2026 Maplesoft, A Division of Waterloo Maple Inc. Maplesoft Document System Wed, 10 Jun 2026 17:38:35 GMT Wed, 10 Jun 2026 17:38:35 GMT The latest answers and comments added to the Question, Problem with initial/boundary conditions solving two PDE's http://www.mapleprimes.com/images/mapleprimeswhite.jpg http://www.mapleprimes.com/questions/141140-Problem-With-Initialboundary-Conditions http://www.mapleprimes.com/questions/141140-Problem-With-Initialboundary-Conditions?ref=Feed:MaplePrimes:Problem with initial/boundary conditions solving two PDE's:Comments#answer141145 <p>You need to write BCS union ICS as they are both sets.<br>There is a simple typographical error in PDE2. The arguments to theta should be x,t not y,x</p> <p>You need to write BCS union ICS as they are both sets.<br>There is a simple typographical error in PDE2. The arguments to theta should be x,t not y,x</p> 141145 Wed, 05 Dec 2012 22:02:47 Z Preben Alsholm Preben Alsholm http://www.mapleprimes.com/questions/141140-Problem-With-Initialboundary-Conditions?ref=Feed:MaplePrimes:Problem with initial/boundary conditions solving two PDE's:Comments#comment141174 <p>Thank you! Now it works great! Always the little things...</p> <p>Just two last small questions:</p> <p>- How do I find the maximum value in a function? Currently I just plot it and measure the peak, but there must be a better way. Just using something like max or extrema doens't really work.</p> <p>- (More important): how do I plot a derative? I need to plot the moment, to obtain the maximum moment. The moment is defined as the derative of theta (I believe). This does not work:</p> <pre>&gt; sol3:-plot(E*J*(diff(theta(x, t), x)), t = 0.188e-1, labels = ['x*[m]', 'M*[Nm]'], title = 'total*moment');</pre> <p>It gives me an empty graph. Changing diff(theta(x, t), x) to D[1](theta)(x, t) does not make a difference.&nbsp;How do I plot a derative?</p> <p><a href="/view.aspx?sf=141174/449474/shear_beam_pin_pin_t.mw">shear_beam_pin_pin_t.mw</a></p> <p>Thank you! Now it works great! Always the little things...</p> <p>Just two last small questions:</p> <p>- How do I find the maximum value in a function? Currently I just plot it and measure the peak, but there must be a better way. Just using something like max or extrema doens't really work.</p> <p>- (More important): how do I plot a derative? I need to plot the moment, to obtain the maximum moment. The moment is defined as the derative of theta (I believe). This does not work:</p> <pre>&gt; sol3:-plot(E*J*(diff(theta(x, t), x)), t = 0.188e-1, labels = ['x*[m]', 'M*[Nm]'], title = 'total*moment');</pre> <p>It gives me an empty graph. Changing diff(theta(x, t), x) to D[1](theta)(x, t) does not make a difference.&nbsp;How do I plot a derative?</p> <p><a href="/view.aspx?sf=141174/449474/shear_beam_pin_pin_t.mw">shear_beam_pin_pin_t.mw</a></p> 141174 Thu, 06 Dec 2012 16:41:19 Z maschoemaker maschoemaker