Fix regressions caused by ismatrix definition change (partial fix bug #47036). * inputdlg.m: Test that linespec isnumeric. * uigetfile.m: Check that position property value isnumeric. * fminunc.m: Check that x0 isnumeric. * fsolve.m: Check that x0 isnumeric. * lsqnonneg.m: Check that inputs C & D are both isnumeric and ismatrix. * pqpnonneg.m: Check that inputs C & D are both isnumeric and ismatrix. * bicg.m: Check input A issquare. Rephrase error messages. * bicgstab.m: Check input A issquare. Rephrase error messages. * cgs.m: Check input A issquare. Rephrase error messages. * gmres.m: Check input A issquare. Rephrase error messages. Change BIST test to match new error message. * qmr.m: Check input A issquare. Rephrase error messages. * spconvert.m: Check nargin first. Simplify input validation. Wrap long error message to < 80 chars. * treeplot.m: Simplify input validation.