## 3 Badges

17 years, 89 days

## missing conditions for dsolve...

this is a follow up on a previous issue i have a rather large differential equation which i can _only_ solve numerically. i have conditions for a boundary value problem to supply to dsolve, but one of them is given in the form of an integral code: ---------------------------------------------- sys:={diff(f(x),x,x)=0,f(0)=1,int(f(x),x=0..1)=0}; > sol:=dsolve(sys,numeric); Error, (in dsolve/numeric/DAE/make_proc) number of unknown functions and equations must match, got 1 functions {f}, and 2 equations ------------------------------------------------------ (the equation is actually a rather large system) Is there a way to make dsolve/numeric work when a condition is supplied in the form of an integral? thanks

## missing conditions for dsolve...

this is a follow up on a previous issue i have a rather large differential equation which i can _only_ solve numerically. i have conditions for a boundary value problem to supply to dsolve, but one of them is given in the form of an integral code: ---------------------------------------------- sys:={diff(f(x),x,x)=0,f(0)=1,int(f(x),x=0..1)=0}; > sol:=dsolve(sys,numeric); Error, (in dsolve/numeric/DAE/make_proc) number of unknown functions and equations must match, got 1 functions {f}, and 2 equations ------------------------------------------------------ (the equation is actually a rather large system) Is there a way to make dsolve/numeric work when a condition is supplied in the form of an integral? thanks

## Perhaps i am missing...

Perhaps i am missing something... but i was under the impression that when you make a plot with a logorithmic scale, you do not calculate the logorithms of the values (of either x, or y) - you merely shrink the axis, so that the units become "logorithmic", eg 1,10,100.. instead of 1,2,3 in your example, maple draws a graph of 2x, and when x=10 (10^1), the value of the function is 20 (slightly above 10^1 on the y axis. so no logorithm is being calculated - only the scale is changed. in that regard, i dont see why it wouldnt be possible to make a plot of, say x = -100,-10,-1,0,1,10,100 ... right now im looking at a printout of such a plot which was generated by maple...so it is actually possible. Ive searched all over and havent been able to find a solution so far.

## Perhaps i am missing...

Perhaps i am missing something... but i was under the impression that when you make a plot with a logorithmic scale, you do not calculate the logorithms of the values (of either x, or y) - you merely shrink the axis, so that the units become "logorithmic", eg 1,10,100.. instead of 1,2,3 in your example, maple draws a graph of 2x, and when x=10 (10^1), the value of the function is 20 (slightly above 10^1 on the y axis. so no logorithm is being calculated - only the scale is changed. in that regard, i dont see why it wouldnt be possible to make a plot of, say x = -100,-10,-1,0,1,10,100 ... right now im looking at a printout of such a plot which was generated by maple...so it is actually possible. Ive searched all over and havent been able to find a solution so far.
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