This expression is too large.

The following error message occurred while using the .m file in simulink. I was going to simulate a 7x7 manipulator with simulink.

get_MassMatrix65

This expression is too large. Store partial results in temporary variables to split the expression into smaller parts.

Is there any other way to break an expression into variables?

Answer 1

[Steven Lord]

If you're generating the code for your block from a symbolic expression using matlabFunction or matlabFunctionBlock, as I suspect is the case, have you disabled optimization by specifying the name-value argument Optimize=false? If so try to re-enable optimization by omitting that name-value argument entirely (to use the default of Optimize=true.)

[Walter Roberson]

Caution:

In several releases, optimize true malfunctioned, sometimes greatly. I have not tested in the two most recent releases.

[진웅 이]

t3206 = t2855+t2856+t2857+t2858+t2859+t2860+t2861+t2862+t2863+t2864+t2865+t2866+t2867+t2868+t2869+t2870+t2871+t2872+t2873+t2874+t2875+t2876+t2877+t2878+t2879+t2880+t2881+t2882+t2883+t2884+t2885+t2886+t2887+t2888+t2889+t2890+t2891+t2892+t2893+t2894+t2895+t2896+t2897+t2898+t2899+t2900+t2901+t2902+t2903+t2904+t2905+t2906+t2907+t2908+t2909+t2910+t2911+t2912+t2913+t2914+t2915+t2916+t2917+t2918+t2919+t2920+t2921+t2922+t2923+t2924+t2925+t2926+t2927+t2928+t2929+t2930+t2931+t2932+t2933+t2934+t2935+t2936+t2937+t2938+t2939+t2940+t2941+t2942+t2943+t2944+t2945+t2946+t2947+t2948+t2949+t2950+t2951+t2952+t2953+t2954+t2955+t2956+t2957+t2958+t2959+t2960+t2961+t2962+t2963+t2964+t2965+t2966+t2967+t2968+t2969+t2970+t2971+t2972+t2973+t2974+t2975+t2976+t2977+t2978+t2979+t2980+t2981+t2982+t2983+t2984+t2985+t2986+t2987+t2988+t2989+t2990+t2991+t2992+t2993+t2994+t2995+t2996+t2997+t2998+t2999+t3000+t3001+t3002+t3003+t3004+t3005+t3006+t3007+t3008+t3009+t3010+t3011+t3012+t3013+t3014+t3015+t3016+t3017+t3018+t3019+t3020+t3021+t3022+t3023+t3024+t3025+t3026+t3027+t3028+t3029+t3030+t3031+t3032+t3033+t3034+t3035+t3036+t3037+t3038+t3039+t3040+t3041+t3042+t3043+t3044+t3045+t3046+t3047+t3048+t3049+t3050+t3051+t3052+t3053+t3054+t3055+t3056+t3057+t3058+t3059+t3060+t3061+t3062+t3063+t3064+t3065+t3066+t3067+t3068+t3069+t3070+t3071+t3072+t3073+t3074+t3075+t3076+t3077+t3078+t3079+t3080+t3081+t3082+t3083+t3084+t3085+t3086+t3087+t3088+t3089+t3090+t3091+t3092+t3093+t3094+t3095+t3096+t3097+t3098+t3099+t3100+t3101+t3102+t3103+t3104+t3105+t3106+t3107+t3108+t3109+t3110+t3111+t3112+t3113+t3114+t3115+t3116+t3117+t3118+t3119+t3120+t3121+t3122+t3123+t3124+t3125+t3126+t3127+t3128+t3129+t3130+t3131+t3132+t3133+t3134+t3135+t3136+t3137+t3138+t3139+t3140+t3141+t3142+t3143+t3144+t3145+t3146+t3147+t3148+t3149+t3150+t3151+t3152+t3153+t3154+t3155+t3156+t3157+t3158+t3159+t3160+t3161+t3162+t3163+t3164+t3165+t3166+t3167+t3168+t3169+t3170+t3171+t3172+t3173+t3174+t3175+t3176+t3177+t3178+t3179+t3180+t3181+t3182+t3183+t3184+t3185+t3186+t3187+t3188+t3189+t3190+t3191+t3192+t3193+t3194+t3195+t3196+t3197+t3198+t3199+t3200+t3201+t3202+t3203+t3204+t3205-t11532-t11534-t11537-t11538-t11540-t11546-t11551-t11554-t11555-t11559-t11560-t11561-t11563-t11567-t11568-t11569-t11573-t11574-t11578-t11580-t11581-t11583-t11584-t11592-t11595-t11601-t11602-t11610-t11618-t11621-t11622-t11628-t11632-t11633-t11634-t11639-t11656-t11662-t11665-t11667-t11668-t11669-t11670-t11671-t11672-t11681-t11684-t11686-t11690-t11697-t11698-t11706-t11707-t11713-t11715-t11717-t11718-t11721-t11727-t11729-t11737-t11738-t11741-t11744-t11745-t11761-t11762-t11763-t11764-t11767-t11768-t11781-t11782-t11783-t11784-t11785-t11786-t11790-t11792-t11794-t11797-t11798-t11799-t11804-t11805-t11806-t11807-t11812-t11817-t11821-t3.*t4.*t7.*t13.*3.731166785767855e-3-t3.*t4.*t5.*t10.*t14.*1.185446863937387e-3-t3.*t4.*t8.*t9.*t14.*5.367504695157484e-3-t3.*t4.*t7.*t8.*t9.*t10.*1.272243011263065e-3-t2.*t3.*t4.*t7.*t13.*t17.*3.55634059181216e-3-t3.*t4.*t5.*t7.*t13.*t15.*1.758741834919224e-3;
    

The above calculation formula is too long, so it seems to be a problem.Splitting the equation using variables solves the problem. Is there a simpler way?

[Walter Roberson]

That does not seem to cause problems when I test ?

t3206 = str2sym('t2855+t2856+t2857+t2858+t2859+t2860+t2861+t2862+t2863+t2864+t2865+t2866+t2867+t2868+t2869+t2870+t2871+t2872+t2873+t2874+t2875+t2876+t2877+t2878+t2879+t2880+t2881+t2882+t2883+t2884+t2885+t2886+t2887+t2888+t2889+t2890+t2891+t2892+t2893+t2894+t2895+t2896+t2897+t2898+t2899+t2900+t2901+t2902+t2903+t2904+t2905+t2906+t2907+t2908+t2909+t2910+t2911+t2912+t2913+t2914+t2915+t2916+t2917+t2918+t2919+t2920+t2921+t2922+t2923+t2924+t2925+t2926+t2927+t2928+t2929+t2930+t2931+t2932+t2933+t2934+t2935+t2936+t2937+t2938+t2939+t2940+t2941+t2942+t2943+t2944+t2945+t2946+t2947+t2948+t2949+t2950+t2951+t2952+t2953+t2954+t2955+t2956+t2957+t2958+t2959+t2960+t2961+t2962+t2963+t2964+t2965+t2966+t2967+t2968+t2969+t2970+t2971+t2972+t2973+t2974+t2975+t2976+t2977+t2978+t2979+t2980+t2981+t2982+t2983+t2984+t2985+t2986+t2987+t2988+t2989+t2990+t2991+t2992+t2993+t2994+t2995+t2996+t2997+t2998+t2999+t3000+t3001+t3002+t3003+t3004+t3005+t3006+t3007+t3008+t3009+t3010+t3011+t3012+t3013+t3014+t3015+t3016+t3017+t3018+t3019+t3020+t3021+t3022+t3023+t3024+t3025+t3026+t3027+t3028+t3029+t3030+t3031+t3032+t3033+t3034+t3035+t3036+t3037+t3038+t3039+t3040+t3041+t3042+t3043+t3044+t3045+t3046+t3047+t3048+t3049+t3050+t3051+t3052+t3053+t3054+t3055+t3056+t3057+t3058+t3059+t3060+t3061+t3062+t3063+t3064+t3065+t3066+t3067+t3068+t3069+t3070+t3071+t3072+t3073+t3074+t3075+t3076+t3077+t3078+t3079+t3080+t3081+t3082+t3083+t3084+t3085+t3086+t3087+t3088+t3089+t3090+t3091+t3092+t3093+t3094+t3095+t3096+t3097+t3098+t3099+t3100+t3101+t3102+t3103+t3104+t3105+t3106+t3107+t3108+t3109+t3110+t3111+t3112+t3113+t3114+t3115+t3116+t3117+t3118+t3119+t3120+t3121+t3122+t3123+t3124+t3125+t3126+t3127+t3128+t3129+t3130+t3131+t3132+t3133+t3134+t3135+t3136+t3137+t3138+t3139+t3140+t3141+t3142+t3143+t3144+t3145+t3146+t3147+t3148+t3149+t3150+t3151+t3152+t3153+t3154+t3155+t3156+t3157+t3158+t3159+t3160+t3161+t3162+t3163+t3164+t3165+t3166+t3167+t3168+t3169+t3170+t3171+t3172+t3173+t3174+t3175+t3176+t3177+t3178+t3179+t3180+t3181+t3182+t3183+t3184+t3185+t3186+t3187+t3188+t3189+t3190+t3191+t3192+t3193+t3194+t3195+t3196+t3197+t3198+t3199+t3200+t3201+t3202+t3203+t3204+t3205-t11532-t11534-t11537-t11538-t11540-t11546-t11551-t11554-t11555-t11559-t11560-t11561-t11563-t11567-t11568-t11569-t11573-t11574-t11578-t11580-t11581-t11583-t11584-t11592-t11595-t11601-t11602-t11610-t11618-t11621-t11622-t11628-t11632-t11633-t11634-t11639-t11656-t11662-t11665-t11667-t11668-t11669-t11670-t11671-t11672-t11681-t11684-t11686-t11690-t11697-t11698-t11706-t11707-t11713-t11715-t11717-t11718-t11721-t11727-t11729-t11737-t11738-t11741-t11744-t11745-t11761-t11762-t11763-t11764-t11767-t11768-t11781-t11782-t11783-t11784-t11785-t11786-t11790-t11792-t11794-t11797-t11798-t11799-t11804-t11805-t11806-t11807-t11812-t11817-t11821-t3.*t4.*t7.*t13.*3.731166785767855e-3-t3.*t4.*t5.*t10.*t14.*1.185446863937387e-3-t3.*t4.*t8.*t9.*t14.*5.367504695157484e-3-t3.*t4.*t7.*t8.*t9.*t10.*1.272243011263065e-3-t2.*t3.*t4.*t7.*t13.*t17.*3.55634059181216e-3-t3.*t4.*t5.*t7.*t13.*t15.*1.758741834919224e-3')

t3206 = 

matlabFunction(t3206, 'file', 't3206.m', 'optimize', false)

ans = function_handle with value:
    @t3206

[Laribi Nessrine]

I have the same problem could you tell me please where i can find "optimization setting" in simulink. Thanks

[Walter Roberson]

@Laribi Nessrine

There is no relevant optimization setting in Simulink. The long expression with t2855 and so on is output from having used matlabFunction on a symbolic expression and having asked it to write to a file. I showed above how to turn off optimization when you do that:

matlabFunction(t3206, 'file', 't3206.m', 'optimize', false)