Bug 1007200

Description of problem:
I was simulating a circuit a circuit with a switch. When I choose transient simulation and edited their type from linear to logarithmic (for curiosity) I got an error. Qucs didn't crash, but appear a warning simulation.

Version-Release number of selected component:
qucs-0.0.17-1.fc20

Additional info:
reporter:       libreport-2.1.6
backtrace_rating: 4
cmdline:        /usr/bin/qucsator -b -g -i /home/brallan/.qucs/netlist.txt -o /home/brallan/qucs/033.dat
crash_function: __assert_fail_base
executable:     /usr/bin/qucsator
kernel:         3.10.10-200.fc19.i686.PAE
runlevel:       N 5
uid:            1000

Truncated backtrace:
[New LWP 15813]
Core was generated by `/usr/bin/qucsator -b -g -i /home/brallan/.qucs/netlist.txt -o /home/brallan/quc'.
Program terminated with signal 6, Aborted.
#0  0xb7707424 in __kernel_vsyscall ()

Thread 1 (LWP 15813):
#0  0xb7707424 in __kernel_vsyscall ()
No symbol table info available.
#1  0x4f2da936 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
        resultvar = <optimized out>
        resultvar = <optimized out>
        pid = 1330016256
        selftid = 15813
#2  0x4f2dc173 in __GI_abort () at abort.c:90
        save_stage = 2
        act = {__sigaction_handler = {sa_handler = 0x0, sa_sigaction = 0x0}, sa_mask = {__val = {0, 1328370958, 1329637427, 1330020676, 1328367536, 0, 3218538563, 137985640, 4294967295, 1328682677, 1329732622, 1330016256, 3218551408, 1328675408, 4, 1330020676, 1328478379, 1330016256, 1329736632, 1330017312, 4224, 1, 1330018656, 1329736632, 3218551448, 1330016256, 1329728445, 1330016256, 1330018656, 0, 3, 4096}}, sa_flags = 1329191400, sa_restorer = 0x4f2dc038 <__GI_abort+8>}
        sigs = {__val = {32, 0 <repeats 31 times>}}
#3  0x4f2d39d7 in __assert_fail_base (fmt=0x4f423bd8 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=assertion@entry=0x8397aea "start * stop > 0", file=file@entry=0x83908a5 "vector.cpp", line=line@entry=951, function=function@entry=0x8397bc0 "vector logspace(double, double, int)") at assert.c:92
        str = 0xa04d258 "qucsator: vector.cpp:951: vector logspace(double, double, int): Assertion `start * stop > 0' failed.\n"
        total = 4096
#4  0x4f2d3a87 in __GI___assert_fail (assertion=0x8397aea "start * stop > 0", file=0x83908a5 "vector.cpp", line=951, function=0x8397bc0 "vector logspace(double, double, int)") at assert.c:101
No locals.
#5  0x080bc06f in logspace(double, double, int) ()
No symbol table info available.
#6  0x080d32ff in logsweep::create(double, double, int) ()
No symbol table info available.
#7  0x08056054 in analysis::createSweep(char const*) ()
No symbol table info available.
#8  0x0809d5db in trsolver::initSteps() ()
No symbol table info available.
#9  0x0809f2c5 in trsolver::solve() ()
No symbol table info available.
#10 0x08054eb8 in net::runAnalysis(int&) ()
No symbol table info available.
#11 0x08049fc0 in main ()
No symbol table info available.
From        To          Syms Read   Shared Object Library
0x4f694e10  0x4f7036e4  Yes         /lib/libstdc++.so.6
0x4f494560  0x4f4bf008  Yes         /lib/libm.so.6
0x4f4f00c0  0x4f505b94  Yes         /lib/libgcc_s.so.1
0x4f2c32d0  0x4f40842c  Yes         /lib/libc.so.6
0x4f289850  0x4f2a213c  Yes         /lib/ld-linux.so.2
$1 = 0xb7703000 ""
No symbol "__glib_assert_msg" in current context.
eax            0x0	0
ecx            0x3dc5	15813
edx            0x6	6
ebx            0x3dc5	15813
esp            0xbfd73144	0xbfd73144
ebp            0xbfd733a0	0xbfd733a0
esi            0xb7703000	-1217384448
edi            0x4f467000	1330016256
eip            0xb7707424	0xb7707424 <__kernel_vsyscall+16>
eflags         0x246	[ PF ZF IF ]
cs             0x73	115
ss             0x7b	123
ds             0x7b	123
es             0x7b	123
fs             0x0	0
gs             0x33	51
Dump of assembler code for function __kernel_vsyscall:
   0xb7707414 <+0>:	push   %ecx
   0xb7707415 <+1>:	push   %edx
   0xb7707416 <+2>:	push   %ebp
   0xb7707417 <+3>:	mov    %esp,%ebp
   0xb7707419 <+5>:	sysenter 
   0xb770741b <+7>:	nop
   0xb770741c <+8>:	nop
   0xb770741d <+9>:	nop
   0xb770741e <+10>:	nop
   0xb770741f <+11>:	nop
   0xb7707420 <+12>:	nop
   0xb7707421 <+13>:	nop
   0xb7707422 <+14>:	int    $0x80
=> 0xb7707424 <+16>:	pop    %ebp
   0xb7707425 <+17>:	pop    %edx
   0xb7707426 <+18>:	pop    %ecx
   0xb7707427 <+19>:	ret    
End of assembler dump.