## 161 Reputation

11 years, 255 days

## How do I get evalf to evaluate when two ...

Maple 11

Hello,

I solved an equation, and Maple returns two values.  Even though I said, assuming v1i>0, the solve command returnse this:

## Cauchy Principle value...

Maple

Hello,

I am wondering if anyone knows why Maple gives different results calling this directly and applying the definition.  For example:

int(1/(4*sin(x)-3*cos(x)), x = -(1/2)*Pi .. (1/2)*Pi, 'CauchyPrincipalValue')

-(2/5)*ln(2)

vs.

limit(Int(1/(4*sin(x)-3*cos(x)), x = -(1/2)*Pi .. arctan(3/4)-e)+Int(1/(4*sin(x)-3*cos(x)), x = arctan(3/4)+e .. (1/2)*Pi), e = 0, right)

-(2/5)*ln(2)-(1/5*I)*Pi

## Integral equations......

Maple

Hello,

I am trying to get Maple to help me solve an integral equation.  I tried the solve command, which I suspected wouldn't work.  I was right, but I do not know how else to approach the problem.  Here is what I did:

solve(int(f(t), t = 1 .. x) = 5*x^2+7*x-3, f(t))

Of course this produced an error.  Any suggestions?  Thank you.

## Cannot find info on this error......

Maple

I am trying to solve this ode numerically in Maple 11.

c:=3;

ode1 := (diff(y(x), x))^2+4*c*(diff(y(x), x))+4*c^2*y(x)/(1-x^2);

dsn3 := dsolve({ics, ode1}, numeric);

But I get the following error:

Error, (in DEtools/convertsys) unable to convert to an explicit first-order system

What does this error mean?  The function y(x) is valid on {0,1}

Thanks.

## plot both an arrow and a function....

Maple

O.k. so I can plot an arrow.  And I can plot a function.  Now how do I get them on the same plot?  Any simple example that shows how to do this will help me.  Thanks.

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