#207 debugging in qucs

[sydney]

I've done a lot of development in other environments such as Eclipse C and C++, Java, Scilab (a free alternative to Matlab), and Sue (a PLL design tool). All these tools have forums with great support. I wish that were true for Qucs: not so. Almost 90% of my posts are ignored. Going through the opamp tutorial (from the help files) recently, I find that almost all the examples have problems. This brought forth the simple fact that debugging in this environment is almost entirely missing. and I do like to use a debugger to figure out where I screwed up. Aside from attaching output posts inside subcircuits and bringing them out to see what is going on inside the complex example, I see no other method for debugging. What do the original developers of these examples do to figure out what they did wrong. No one makes code without making mistakes. Looking at the netlist sometimes helps, other times it just adds to the perplexity of trying to figure out what is wrong with the code. The messages are, so say the least, very confusing other than to mention the line number causing the problem. Also, I would like to mention that the opamps tutorial needs a review. This tutorial is from the help files. In the first part of the tutorial, we create a simple opamp from three sub circuits. We use a few VCCS and CCCS with gains of S=1 and R=1. The example simply doesn't work according to the tutorial. The quiescent point is screw up and the graphs are flat lines. The gain and phase are screwed up! Realizing that an ideal opamp has an infinite gain, I monkeyed around with the gain factors in the sources and changed them to 1M! Voila, the quiescent point is now right on. Doing a transient analysis shows the output to be 20 dB and the phase to be -180, which is as it should be. Good so far. But the AC simulation is still a flat line, so there is still a problem. Since all the other tutorials rely on this example, I'm stymied here. I did plod on through the rest of the tutorial, and found other errors of ommission in this article: in figures 28, 25, and 22, there are diagrams on how to make a part of the ultimate opamp circuit. Each of these figures is followed by a test setup diagram containing the new opamp, which has been obtained from a previous opamp model using the new cell. But no diagram showing how to make the modified opamp. One can go back to the beginning of the tutorial and see a block diagram of the intended final opamp. And from that surmise how to create the opamp from the preceding opamp model. The modified diagram should be in plain site, before the test diagram. But no diagram at all. This tool is quite nice, but without any support from the forum, it is nearly impossible to develop in this enviroment, especially without debugging tools. Maybe the powers that be, could get together and develop a tutorial about fixing mistakes when developing. Or provide some debugging information.