## 894 Reputation

17 years, 258 days

## MaplePrimes Activity

These are Posts that have been published by brian bovril

## Global Non Linear Program?...

Just wonder if anyone knows how I can improve on minimizing this large poly, subject to constraints: Download The minimum found was 82.7 It has found a local minima, but there must be a global minima. Do i really have to splash out on the GOT package?

## NLPSolve - binomial...

Wonder is someone can help I need to Minimize the non-linear objective function: Obj:=(1/4*a[1]+3/4*a[2]+7/8*a[3]+15/8*a[5]+2*a[6]+19/8*a[7]+21/8*a[8]+1/4*b[1]+ 3/4*b[2]+7/8*b[3]+15/8*b[5]+2*b[6]+19/8*b[7]+21/8*b[8])^2 subject to the following constraints: CON1:=add(a[n],n=1..8)=4 CON2:=add(b[n],n=1..8)=4 CON3:=seq(a[n]+b[n]=1,n=1..8) CON4:=seq(or(a[n]=0,b[n]=1),n=1..8) With(Optimization): NLPSolve(Obj,{CON1,CON2,CON3,CON4},assume = nonnegative); produces this: Error, (in Optimization:-NLPSolve) constraints must be specified as a set or list of equalities and inequalities

## triangle in ellipse...

Does anyone know how to work out the largest triangle that can be enclosed within an ellipse (both in 2D)? For any triangle, Area:=sqrt(s*(s-a)*(s-b)*(s-c)) where s:=(a+b+c)/2 and a,b,c are the length of the sides. Say the ellipse is equation 1/9*x^2+1/4*y^2 = 1 hence y: = -2/3*(-x^2+9)^(1/2) or +2/3*(-x^2+9)^(1/2) Given three points (x1,y1), (x2,y2), (x3,y3) Eg distance from (-x1,-y) to (-x2,y) with(student): a:=distance([-x1, subs(x=-x1,-2/3*(-x^2+9)^(1/2) )], [-x2, subs(x=-x2, +2/3*(-x^2+9)^(1/2))]); (note the sign of y) and so forth for b and c. there has to be a more eloquent (calculus) way.

## Total Derivative...

Hi I wonder if anyone can assist with the Maple commmand to do total derivatives. For example, tan(theta)=1/x I want to know if there is a direct command to differentiate this equation w.r.t t (time). From memory, if I input D(tan(theta)=1/x), Maple outputs: tan(theta)D(theta)=-1/x^2 Dx the correct result should be: sec^2(theta)d(theta)/dt = -1/x^2 dx/dt thanks in advance Brian
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